Kawasaki Ninja 250R Motorcycle. Service Manual (2008-2012 year)

ENGINE TOP END 5-1

Engine Top End

Table of Contents

Exploded View

5-2

Cylinder Head Removal

5-23

Exhaust System

5-6

Cylinder Head Installation

5-23

Specifications

5-8

Cylinder Head Warp Inspection ...

5-24

Special Tools and Sealant

5-10

Cylinder Head Cleaning

5-25

Clean Air System

5-12

Valves

5-26

Vacuum Switch Valve Removal ...

5-12

Valve Clearance Inspection

5-26

Vacuum Switch Valve Installation

5-12

Valve Clearance Adjustment

5-26

Vacuum Switch Valve Operation

Valve Removal

5-26

Test

5-12

Valve Installation

5-26

Vacuum Switch Valve Unit Test

5-12

Valve Guide Removal

5-26

Air Suction Valve Removal

5-13

Valve Guide Installation

5-26

Air Suction Valve Installation

5-13

Valve-to-Guide Clearance

Air Suction Valve Inspection

5-13

Measurement (Wobble

Clean Air System Hose

Method)

5-27

Inspection

5-14

Valve Seat Inspection

5-28

Cylinder Head Cover

5-15

Valve Seat Repair

5-28

Cylinder Head Cover Removal

5-15

Cylinder, Pistons

5-33

Cylinder Head Cover Installation .

5-15

Cylinder Removal

5-33

Camshaft Chain Tensioner

5-16

Cylinder Installation

5-33

Camshaft Chain Tensioner

Piston Removal

5-34

Removal

5-16

Piston Installation

5-34

Camshaft Chain Tensioner

Cylinder Wear Inspection

5-35

Installation

5-16

Piston Wear Inspection

5-35

Camshaft, Camshaft Chain

5-18

Piston Ring, Piston Ring Groove

Camshaft Removal

5-18

Wear Inspection

5-36

Camshaft Installation

5-18

Piston Ring Groove Width

Camshaft and Sprocket

Inspection

5-36

Assembly

5-20

Piston Ring Thickness Inspection

5-36

Camshaft and Camshaft Cap

Piston Ring End Gap Inspection..

5-37

Wear Inspection

5-20

Boring, Honing

5-37

Camshaft Runout Inspection

5-21

Carburetor Holder

5-38

Cam Wear Inspection

5-21

Carburetor Holder Installation

5-38

Camshaft Chain Guide Wear

Muffler

5-39

Inspection

5-21

Muffler Removal

5-39

Cylinder Head

5-22

Muffler Installation

5-39

Cylinder Compression

Exhaust System Inspection

5-40

Measurement

5-22

ENGINE TOP END 5-3

Exploded View

Torque

No.

Fastener

Remarks

N·m

kgf·m

ft·lb

Cylinder Head Cover Bolts

9.8

1.0

87 in·lb

Camshaft Sprocket Bolts

1.5

Chain Tensioner Cap Bolt

5.0

0.5

44 in·lb

Air Suction Cover Bolts

9.8

1.0

87 in·lb

Vacuum Switch Valve Bracket Bolts

9.8

1.0

87 in·lb

Rear Camshaft Chain Guide Bolt-Lower

1.7

Chain Tensioner Mounting Bolts

9.8

1.0

87 in·lb

EO: Apply engine oil.

L: Apply a non-permanent locking agent.

M: Apply molybdenum disulfide grease.

MO: Apply molybdenum disulfide oil solution (mixture of the engine oil and molybdenum disufide

grease in a weight ratio 10 : 1).

R: Replacement Parts

SS: Apply silicon sealant.

ENGINE TOP END 5-5

Exploded View

Torque

No.

Fastener

Remarks

N·m

kgf·m

ft·lb

Camshaft Cap Bolts

1.2

106 in·lb

Cylinder Head Bolt (M6)

1.2

106 in·lb

Cylinder Head Bolts (M8)

31.4

3.2

MO, S

Water Passage Plugs

2.0

Carburetor Holder Clamp Screws

2.0

0.2

18 in·lb

Water Drain Bolt

5.9

0.6

52 in·lb

Muffler Body Rear Cover Bolts

9.8

1.0

87 in·lb

Muffler Body Mounting Bolt

3.1

Muffler Body Clamp Bolt

1.7

Muffler Cover Bolts

9.8

1.0

87 in·lb

Muffler Cover Clamp Screw

6.9

0.70

61 in·lb

Exhaust Pipe Mounting Bolt

9.8

1.0

87 in·lb

Exhaust Pipe Holder Nuts

1.2

104 in·lb

Exhaust Pipe Chamber Clamp Screw

9.8

1.0

87 in·lb

15. EX250J8

16. EX250J8 ∼ JA

L: Apply a non-permanent locking agent.

MO: Apply molybdenum disulfide oil solution (mixture of the engine oil and molybdenum disufide

grease in a weight ratio 10 : 1).

S: Follow the specific tightening sequence.

5-8 ENGINE TOP END

Specifications

Item

Standard

Service Limit

Clean Air System

Vacuum Switch Valve

Open → Close

Closing Pressure

41.3 ∼ 49.3 kPa (310 ∼ 370 mmHg)

- - -

Camshafts, Camshaft Chain,

Rocker Arms

Cam Height:

Exhaust

32.843 ∼ 32.957 mm (1.2930 ∼ 1.2975 in.)

32.74 mm (1.289 in.)

Inlet

33.843 ∼ 33.957 mm (1.3324 ∼ 1.3369 in.)

33.74 mm (1.328 in.)

Camshaft Journal, Camshaft

0.028 ∼ 0.071 mm (0.0011 ∼ 0.0028 in.)

0.16 mm (0.0063 in.)

Cap Clearance

Camshaft Journal Diameter

23.950 ∼ 23.972 mm (0.9429 ∼ 0.9438 in.)

23.92 mm (0.942 in.)

Camshaft Bearing Inside

24.000 ∼ 24.021 mm (0.9449 ∼ 0.9457 in.)

24.08 mm (0.948 in.)

Diameter

Camshaft Runout

TIR 0.02 mm (0.0008 in.) or less

TIR 0.1 mm (0.004 in.)

Cylinder Head

Cylinder Compression

(Usable Range)

980 ∼ 1 500 kPa (10.0 ∼ 15.3 kgf/cm², 142

- - -

∼ 218 psi) @470 r/min (rpm)

Cylinder Head Warp

---

0.05 mm (0.002 in.)

Valves

Valve Clearance:

Inlet

0.15 ∼ 0.24 mm (0.0059 ∼ 0.0094 in.)

- - -

Exhaust

0.22 ∼ 0.29 mm (0.0087 ∼ 0.0114 in.)

- - -

Valve Head Thickness:

Inlet

0.50 mm (0.0197 in.)

0.3 mm (0.012 in.)

Exhaust

0.80 mm (0.0315 in.)

0.5 mm (0.020 in.)

Valve Stem Bend

TIR 0.01 mm (0.0004 in.) or less

TIR 0.05 mm (0.002 in.)

Valve Stem Diameter:

Inlet

4.475 ∼ 4.490 mm (0.1762 ∼ 0.1768 in.)

4.46 mm (0.176 in.)

Exhaust

4.455 ∼ 4.470 mm (0.1754 ∼ 0.1760 in.)

4.44 mm (0.175 in.)

Valve Guide Inside Diameter

4.500 ∼ 4.512 mm (0.1772 ∼ 0.1776 in.)

4.58 mm (0.180 in.)

Valve/valve Guide Clearance

(Wobble Method):

Inlet

0.03 ∼ 0.09 mm (0.0012 ∼ 0.035 in.)

0.27 mm (0.011 in.)

Exhaust

0.08 ∼ 0.15 mm (0.0031 ∼ 0.0059 in.)

0.33 mm (0.013 in.)

Valve Seating Surface:

Outside Diameter:

Inlet

21.9 ∼ 22.1 mm (0.8622 ∼ 0.8701 in.)

- - -

Exhaust

19.3 ∼ 19.5 mm (0.7598 ∼ 0.7677 in.)

- - -

Width

0.5 ∼ 1.0 mm (0.0197 ∼ 0.0394 in.)

- - -

Valve Spring Free Length:

Inlet

39.5 mm (1.555 in.)

38.0 mm (1.50 in.)

Exhaust

39.5 mm (1.555 in.)

38.0 mm (1.50 in.)

Valve Seat Cutting Angle

32°, 45°, 67.5°

- - -

ENGINE TOP END 5-9

Specifications

Item

Standard

Service Limit

Cylinder, Pistons

Cylinder Inside Diameter

62.000 ∼ 62.012 mm (2.4409 ∼ 2.4414 in.)

62.10 mm (2.44 in.)

Piston Diameter

61.942 ∼ 61.957 mm (2.4387 ∼ 2.4392 in.)

61.80 mm (2.43 in.)

Piston/Cylinder Clearance

0.043 ∼ 0.070 mm (0.0017 ∼ 0.0028 in.)

- - -

Oversize Pistons and Rings

+0.5 mm (0.020 in.)

- - -

Piston Ring/Groove

Clearance:

Top

0.03 ∼ 0.07 mm (0.0012 ∼ 0.0028 in.)

0.17 mm (0.0067 in.)

Second

0.02 ∼ 0.06 mm (0.0008 ∼ 0.0024 in.)

0.16 mm (0.0063 in.)

Piston Ring Groove Width:

Top

0.82 ∼ 0.84 mm (0.0323 ∼ 0.0331 in.)

0.92 mm (0.0362 in.)

Second

0.81 ∼ 0.83 mm (0.0319 ∼ 0.0327 in.)

0.91 mm (0.0358 in.)

Oil

1.51 ∼ 1.53 mm (0.0594 ∼ 0.0602 in.)

1.61 mm (0.0634 in.)

Piston Ring Thickness:

Top, Second

0.77 ∼ 0.79 mm (0.0303 ∼ 0.0311 in.)

0.7 mm (0.028 in.)

Piston Ring End Gap:

Top

0.15 ∼ 0.30 mm (0.0059 ∼ 0.0118 in.)

0.6 mm (0.024 in.)

Second

0.40 ∼ 0.55 mm (0.0157 ∼ 0.0217 in.)

0.9 mm (0.035 in.)

Oil

0.20 ∼ 0.80 mm (0.0079 ∼ 0.0315 in.)

1.1 mm (0.043 in.)

5-10 ENGINE TOP END

Special Tools and Sealant

Compression Gauge, 20 kgf/cm²:

Valve Seat Cutter Holder Bar:

57001-221

57001-1128

Valve Spring Compressor Assembly:

Valve Seat Cutter, 32° -

22:

57001-241

57001-1206

Piston Pin Puller Assembly:

Valve Seat Cutter, 67.5° -

22:

57001-910

57001-1207

Valve Seat Cutter, 45° -

24.5:

Valve Spring Compressor Adapter,

16:

57001-1113

57001-1305

Valve Seat Cutter, 32° -

25:

Compression Gauge Adapter, M10 × 1.0:

57001-1118

57001-1317

5-12 ENGINE TOP END

Clean Air System

Vacuum Switch Valve Removal

• Remove:

Fuel Tank (see Fuel Tank Removal in the Fuel System

Chapter)

Vacuum Switch Valve Hose Ends [A]

Vacuum Switch Valve [B]

Vacuum Switch Valve Installation

• Install the vacuum switch valve so that the vacuum hose

fitting [A] faces downwards (see Cable, Wire, and Hose

Routing in the Appendix chapter).

NOTE

○This hose fitting [B] side is plugged.

Vacuum Switch Valve Operation Test

• Refer to Air Suction System Damage Inspection in the

Periodic Maintenance chapter (see Air Suction System

Damage Inspection in the Periodic Maintenance chapter).

Vacuum Switch Valve Unit Test

• Remove the fuel tank (see Fuel Tank Removal in the Fuel

System chapter).

○Do not remove the vacuum switch valve.

• Connect a vacuum gauge [A] and syringe [B] or the fork

oil level gauge to the vacuum hose as shown.

Special Tool - Fork Oil Level Gauge: 57001-1290

Air Flow [C]

• Gradually raise the vacuum (lower the pressure) applied

to the vacuum switch valve, and check the valve opera-

tion. When the vacuum is low, the vacuum switch valve

should permit air to flow. When the vacuum is raised to

valve closing pressure, the valve should stop air flow.

Spring [A]

Diaphragm [B]

Valve [C]

Low Vacuum [D]

Secondary Air Flow [E]

ENGINE TOP END 5-13

Clean Air System

If the vacuum switch valve does not operate as described,

replace it with a new one.

NOTE

○To check air flow through the vacuum switch valve, just

blow through the vacuum switch hose [C].

Vacuum Switch Valve Closing Pressure (Open → Close)

Standard:

41.3 ∼ 49.3 kPa (310 ∼ 370 mmHg)

High Vacuum [A]

Secondary air cannot flow [B]

Air Suction Valve Removal

• Remove:

Fuel Tank (see Fuel Tank Removal in the Fuel System

chapter)

Vacuum Switch Valve (see Vacuum Switch Valve Re-

moval)

• Unscrew the bolts [A] and remove the air suction valve

covers [B].

Air Suction Valve Installation

• Install the air suction valve [A] so that its reed opening

side [B] faces backwards.

Torque - Air Suction Valve Cover Bolts : 9.8 N·m (1.0 kgf·m,

87 in·lb)

Air Suction Valve Inspection

• Remove the air suction valve (see Air Suction Valve Re-

moval).

• Visually inspect the reeds for cracks, folds, warps, heat

damage or other damage.

If there is any doubt as to the condition of the reeds [A],

replace the air suction valve as an assembly.

• Check the reed contact areas [B] of the valve holder for

grooves, scratches, any signs of separation from the

holder or heat damage.

• If there is any doubt as to the condition of the reed contact

areas, replace the air suction valve as an assembly.

• If any carbon or other foreign particles have accumulated

between the reed and the reed contact area, wash the

valve assembly clean with a high-flash point solvent.

NOTICE

Do not scrape off the deposits with a scraper as this

could damage the rubber, requiring replacement of

the suction valve assembly.

ENGINE TOP END 5-15

Cylinder Head Cover

Cylinder Head Cover Removal

• Drain the Coolant (see Coolant Change in the Periodic

Maintenance chapter).

• Remove:

Spark Plug Caps

Radiator [A] (see Radiator and Radiator Fan Removal in

the Cooling System chapter)

• Disconnect the primary lead [B] and ground lead [C] con-

nectors of the #2(right) ignition coil [D].

• Remove the right engine bracket mounting bolts [E], and

remove the engine bracket with the right ignition coil.

• Disconnect the air suction valve hose.

• Remove the cylinder head cover bolts [A].

• Remove the cylinder head cover [B].

Cylinder Head Cover Installation

• Scrape off the old gasket [A] on the cylinder head mating

surface, and apply liquid gasket [A] on the mating surface.

Sealant - Liquid Gasket, TB1216B: 92104-1064

• Be sure the water pipe [B] is in place.

• Be sure the damper [A] on the water pipe is in position.

• Install the new cylinder head cover gasket and install the

cylinder head cover with the specified torque.

Torque - Cylinder Head Cover Bolts: 9.8 N·m (1.0 kgf·m, 87

in·lb)

• Install the removed parts.

5-16 ENGINE TOP END

Camshaft Chain Tensioner

Camshaft Chain Tensioner Removal

NOTICE

This is a non-return type camshaft chain tensioner.

The push rod does not return to its original position

once it moves out to take up camshaft chain slack.

Observe all the rules listed below:

When removing the tensioner, do not take out the

mounting bolts only halfway. Retightening the

mounting bolts from this position could damage

the tensioner and the camshaft chain. Once the

bolts are loosened, the tensioner must be removed

and reset as described in “Camshaft Chain Ten-

sioner Installation”.

Do not turn over the crankshaft while the tensioner

is removed. This could upset the camshaft chain

timing and damage the valves.

• Remove the right lower fairing (see Lower Fairing Re-

moval in the Frame chapter).

• Loosen the cap bolt [A]

• Remove the tensioner mounting bolts [B], and remove the

chain tensioner body [C].

Camshaft Chain Tensioner Installation

• Remove the tensioner cap bolt and O-ring.

• While compressing the push rod [A], turn it clockwise with

a suitable screwdriver until the rod stopped.

NOTICE

Do not turn the rod counterclockwise before in-

stalling the tensioner. This could detach the rod

and the tensioner cannot be reinstalled.

• While holding the rod in position with a suitable push rod

holder plate [A] install the tensioner on the cylinder block.

5-18 ENGINE TOP END

Camshaft, Camshaft Chain

Camshaft Removal

• Remove the cylinder head cover (see Cylinder Head

Cover Removal).

• Remove the inspection plugs on the alternator cover.

• Position the crankshaft at #2 piston TDC.

○Using a wrench on the crankshaft rotation bolts, turn the

crankshaft clockwise until the “2T” mark [A] on the alterna-

tor rotor is aligned with the projection [B] in the inspection

window on the alternator cover.

• Remove:

Camshaft Chain Tensioner (see Camshaft Chain Ten-

sioner Removal).

Camshaft Cap Bolts [A]

Plates

Camshaft Top Chain Guide [B]

Camshaft Caps [C]

Camshafts [D]

• Stuff a clean cloth into the camshaft chain tunnel to keep

any parts from dropping into the crankcase.

NOTICE

The crankshaft may be turned while the camshafts

are removed.

Always pull the chain taut while turning the crank-

shaft. This avoids kinking the chain on the lower

(crankshaft) sprocket. A kinked chain could dam-

age both the chain and the sprocket.

Camshaft Installation

• Apply molybdenum disulfide oil solution to the cam and

journal surfaces.

NOTE

○Be sure to operate from the engine left side.

• Position the crankshaft at #2 piston TDC (see Camshaft

Removal).

NOTICE

The crankshaft may be turned while the camshafts

are removed.

Always pull the chain taut while turning the crank-

shaft. This avoids kinking the chain on the lower

(crankshaft) sprocket. A kinked chain could dam-

age both the chain and the sprocket.

ENGINE TOP END 5-19

Camshaft, Camshaft Chain

• Engage the camshaft chain [A] with the camshaft sprock-

ets.

○Pull the tension side (exhaust side) of the chain taut to

install the chain on the sprockets.

○Timing marks [B] align with the cylinder head upper sur-

face.

Exhaust Camshaft Sprocket [C]

Inlet Camshaft Sprocket [D]

○Count the camshaft chain link pins as shown to verify that

the sprocket are positioned correctly.

marks [A].

• Place the six dowel pins on the

• Install the camshaft caps as shown, noting the “EX” [B]

and “IN” [C] marks.

NOTICE

The camshaft caps are machined with the cylinder

head. So, if a cap is installed in a wrong location,

the camshaft may seize because of improper oil

clearance in the bearings.

• Put the plates on the bearing caps.

○The exhaust side plates [A] is longer the inlet side plates

[B].

• First tighten down the chain guide [A] and bearing caps

[B] evenly to seat the camshafts in place, then tighten all

bolts following the specified tightening sequence.

Torque - Camshaft Cap Bolts: 12 N·m (1.2 kgf·m, 106 in·lb)

Plates (EX) [C]

Plates (IN) [D]

• Install the camshaft chain tensioner (see Camshaft Chain

Tensioner Installation).

• Check the chain timing.

• Finally, inject [A] engine oil into 8 places on the cylinder

head, as shown.

5-20 ENGINE TOP END

Camshaft, Camshaft Chain

Camshaft and Sprocket Assembly

• Install the cam sprockets as shown in figure.

Exhaust Cam Sprocket [A]

Inlet Cam Sprocket [B]

• Apply a non-permanent locking agent to the camshaft

sprocket bolts and tighten them.

Torque - Camshaft Sprocket Bolts: 15 N·m (1.5 kgf·m, 11

ft·lb)

If a new camshaft is to be used, apply a thin coat of a

molybdenum disulfide grease to the cam surfaces.

NOTE

○The exhaust camshaft has a groove [A] and the inlet

camshaft has no groove. Be careful not to mix up these

shafts.

Camshaft and Camshaft Cap Wear Inspection

• Remove:

Camshaft Top Guide

Camshaft Caps

• Cut the strips of plastigauge to journal parallel to the

camshaft installed in the correct position.

• Measure each clearance between the camshaft journal

and the camshaft cap using the plastigauge (press gauge)

[A].

• Tighten:

Torque - Camshaft Cap Bolts: 12 N·m (1.2 kgf·m, 106 in·lb)

NOTE

○Do not turn the camshaft when the plastigauge is be-

tween the journal and camshaft cap.

Camshaft Journal, Camshaft Cap Clearance

Standard:

0.028 ∼ 0.071 mm (0.0011 ∼ 0.0028 in.)

Service Limit: 0.16 mm (0.0063 in.)

If any clearance exceeds the service limit, measure the

diameter of each camshaft journal with a micrometer.

Camshaft Journal Diameter

Standard:

23.950 ∼ 23.972 mm (0.9429 ∼ 0.9438 in.)

Service Limit: 23.92 mm (0.942 in.)

If the camshaft journal diameter is less than the service

limit, replace the camshaft with a new one and measure

the clearance again.

If the clearance still remains out of the service limit, re-

place the cylinder head unit.

ENGINE TOP END 5-21

Camshaft, Camshaft Chain

Camshaft Runout Inspection

• Remove the camshaft.

• Set the camshaft in a camshaft alignment jig or on V

blocks.

• Measure the runout with a dial gauge at the specified

place as shown.

If the runout exceeds the service limit, replace the shaft.

Camshaft Runout

Standard:

TIR 0.02 mm (0.0008 in.)

Service Limit: TIR 0.1 mm (0.004 in.)

Cam Wear Inspection

• Remove the camshaft (see Camshaft Removal).

• Measure the height [A] of each cam with a micrometer.

If the cams are worn down past the service limit, replace

the camshaft.

Cam Height

Standard:

Exhaust

32.843 ∼ 32.957 mm (1.2930 ∼ 1.2975 in.)

Inlet

33.843 ∼ 33.957 mm (1.3324 ∼ 1.3369 in.)

Service Limit:

Exhaust

32.74 mm (1.289 in.)

Inlet

33.74 mm (1.328 in.)

Camshaft Chain Guide Wear Inspection

• Visually inspect the rubber [A] on the guide.

• If the rubber is damaged or cut, replace the guides.

5-22 ENGINE TOP END

Cylinder Head

Cylinder Compression Measurement

NOTE

○Use the battery which is fully charged.

• Warm up the engine thoroughly.

• Stop the engine.

• Remove:

Front Seat (see Front Seat Removal in the Frame chap-

ter)

Fuel Tank (see Fuel Tank Removal in the Fuel System

chapter)

Spark Plug (see Spark Plug Replacement in the Periodic

Maintenance chapter)

• Attach the compression gauge [A] and adapter [B] firmly

into the spark plug hole.

• Using the starter motor, turn the engine over with the throt-

tle fully open until the compression gauge stops rising; the

compression is the highest reading obtainable.

Special Tools - Compression Gauge, 20 kgf/cm²: 57001-221

Compression Gauge Adapter, M10 × 1.0:

57001-1317

Cylinder Compression

Usable Range: 961 ∼ 1 471 kPa (9.8 ∼ 15.0 kgf/cm², 139

∼ 213 psi) @470r/min (rpm)

• Repeat the measurement for the other cylinder.

• Install the spark plugs.

Torque - Spark Plugs: 13 N·m (1.3 kgf·m, 115 in·lb)

Problem

Diagnosis

Remedy (Action)

Cylinder

Carbon accumulation on piston and in

Remove the carbon deposits

compression is

combustion chamber possibly due to

and replace damaged parts if

higher than usable

damaged valve stem oil seal and/or

necessary.

range

damaged piston oil rings (This may be

indicated by white exhaust smoke.)

Incorrect cylinder head gasket thickness

Replace the gasket with a

standard part.

Cylinder

Gas leakage around cylinder head

Replace damaged gasket and

compression is

check cylinder head warp.

lower than usable

Bad condition of valve seating

Repair if necessary.

range

Incorrect valve clearance

Adjust the valve clearance.

Incorrect piston/cylinder clearance

Replace the piston and/or cylinder

Piston seizure

Inspect the cylinder and

replace/repair the cylinder

and/or piston as necessary.

Bad condition of piston ring and/or piston

Replace the piston and/or the

ring grooves

piston rings.

ENGINE TOP END 5-23

Cylinder Head

Cylinder Head Removal

• Drain the coolant (see Coolant Change in the Periodic

Maintenance chapter).

• Remove:

Lower Fairing (see Lower Fairing Removal in the Frame

chapter)

Fuel Tank (see Fuel Tank Removal in the Fuel System

chapter)

Radiator (see Radiator, Radiator Fan Removal in the

Cooling System chapter)

Muffler (see Muffler Removal)

Camshaft Chain Tensioner (see Camshaft Chain Ten-

sioner Removal)

Left and Right Engine Bracket with Ignition Coils

• Remove:

Cylinder Head Cover

Camshafts

Rear Camshafts Chain Guide Bolt (Lower) [A] and Chain

Guide [B]

Front Camshaft Chain Guide [C]

• Pull out the water pipe.

• Remove the 6 mm cylinder head bolt [A] first, then remove

the 8 mm cylinder head bolts.

• Remove the oil hose banjo bolt [B].

• Before removing the cylinder head, hold the carburetor to

the air cleaner ducts securely.

Cylinder Head Installation

NOTE

○The camshaft cap is machined with the cylinder head,

so if a new cylinder head is installed, use the cap that

is supplied with the new head.

• Install the pin and new cylinder head gasket.

• Apply molybdenum disulfide oil to the both sides [A] of the

8 mm cylinder head bolt washers.

5-24 ENGINE TOP END

Cylinder Head

• Tighten the 8 mm cylinder head bolts [1 ∼ 7] following the

tightening sequence.

Torque - Cylinder Head Bolts: 31.4 N·m (3.2 kgf·m, 23 ft·lb)

• Tighten the 6 mm cylinder head bolt [8] following the tight-

ening sequence.

Torque - Cylinder Head Bolts: 12 N·m (1.2 kgf·m, 106 in·lb)

• After cylinder head installation, install the front camshaft

chain guide [A].

• Tighten the rear camshaft chain guide bolt (lower) [B] to

the specified torque.

• Tighten the oil hose banjo bolt to the specified torque.

Torque - Camshaft Chain Guide Bolt (lower): 17 N·m (1.7

kgf·m, 13 ft·lb)

Oil Hose Banjo Bolt: 19.6 N·m (2.0 kgf·m, 14.5 ft·lb)

Cylinder Head Warp Inspection

• Lay a straightedge across the lower surface of the cylinder

head at several positions.

• Use a thickness gauge [A] to measure the space between

the straightedge [B] and the head.

Cylinder Head Warp

Standard:

- - -

Service Limit: 0.05 mm (0.002 in.)

If the cylinder head is warped more than the service limit,

replace it.

If the cylinder head is warped less than the service limit,

repair the head by rubbing the lower surface on emery

paper secured to a surface plate (first No. 200, then No.

400).

ENGINE TOP END 5-25

Cylinder Head

Cylinder Head Cleaning

• Remove:

Cylinder Head (see Cylinder Head Removal)

Valves (see Valve Removal)

• Scrape [A] the carbon out of the combustion chamber and

exhaust port with a suitable tool.

• Wash the cylinder head with a high-flash point solvent.

• Using compressed air, blow out any particles which may

obstruct the oil passage [A] in the cylinder head.

• Install the valve (see Valve Installation).

• Install the cylinder head (see Cylinder Head Installation).

5-26 ENGINE TOP END

Valves

Valve Clearance Inspection

• Refer to Valve Clearance Inspection in the Periodic Main-

tenance chapter.

Valve Clearance Adjustment

• Refer to Valve Clearance Adjustment in the Periodic

Maintenance chapter.

Valve Removal

• Remove the cylinder head (see Cylinder Head Removal).

• Use the valve spring compressor assembly and the

adapter to press down the valve spring retainer.

Special Tools - Valve Spring Compressor Assembly: 57001

-241 [A]

Valve Spring Compressor Adapter,

16:

57001-1305 [B]

Valve Installation

• Replace the oil seal with a new one.

• Apply engine oil to the lip of oil seal.

• Apply a thin coat of molybdenum disulfide grease to the

valve stem before valve installation.

• Install the spring so that the closed coil end faces down-

wards.

[A] Valve Stem

[E] Retainer

[B] Spring Seat

[F] Split Keepers

[C] Spring

[G] Closed Coil End

[D] Oil Seal

Valve Guide Removal

• Remove:

Valve (see Valve Removal)

Oil Seal

Spring Seat

• Heat the area around the valve guide to 120 ∼ 150°C (248

∼ 302°F), and hammer lightly on the valve guide arbor [A]

to remove the guide from the top of the head.

NOTICE

Do not heat the cylinder head with a torch. This will

warp the cylinder head. Soak the cylinder head in

oil and heat the oil.

Special Tool - Valve Guide Arbor,

4.5: 57001-1331

Valve Guide Installation

• Apply a thin coat of oil to the outer surface of the valve

guide.

• Heat the area around the valve guide up to 120 ∼ 150°C

(248 ∼ 302°F).

NOTICE

Do not heat the cylinder head with a torch. This will

warp the cylinder head. Soak the cylinder head and

heat the oil.

ENGINE TOP END 5-27

Valves

• Using the valve guide driver [A] and washer [B], press

and insert the valve guide in until the washer surface [C]

touches the head surface [D].

15.3 ∼ 15.5 mm (0.60 ∼ 0.61 in.) [E]

Special Tools - Valve Guide Drive: 57001-1564

Washer: 57001-1720

• Wait until the cylinder head cools down and then ream the

valve guide with the valve guide reamer [A] even if the old

guide is reused.

○Turn the reamer in a clockwise direction until the reamer

turns freely in the guide. Never turn the reamer counter-

clockwise or it will be dulled.

○Once the guides are reamed they must be cleaned thor-

oughly.

Special Tool - Valve Guide Reamer,

4.5: 57001-1333

Valve-to-Guide Clearance Measurement (Wobble

Method)

If a small bore gauge is not available, inspect the valve

guide wear by measuring the valve to valve guide clearance

with the wobble method as indicated below.

• Insert a new valve [A] into the guide [B] and set a dial

gauge against the stem perpendicular to it as close as

possible to the cylinder head mating surface.

• Move the stem back and forth [C] to measure valve/valve

guide clearance.

• Repeat the measurement in a direction at a right angle to

the first.

If the reading exceeds the service limit, replace the guide.

NOTE

○The reading is not actual valve/valve guide clearance

because the measuring point is above the guide.

Valve/Valve Guide Clearance (Wobble Method)

Standard:

Inlet

0.03 ∼ 0.09 mm (0.0012 ∼ 0.0035 in.)

Exhaust

0.08 ∼ 0.15 mm (0.0031 ∼ 0.0059 in.)

Service Limit:

Inlet

0.27 mm (0.011 in.)

Exhaust

0.33 mm (0.013 in.)

5-28 ENGINE TOP END

Valves

Valve Seat Inspection

• Remove the valve (see Valve Removal).

• Check the valve seating surface [A] between the valve [B]

and valve seat [C].

○Measure the outside diameter [D] of the seating pattern

on the valve seat.

If the outside diameter is too large or too small, repair the

seat (see Seat Repair).

Valve Seating Surface Outside Diameter

Standard:

Inlet

21.9 ∼ 22.1 mm (0.8622 ∼ 0.8701 in.)

Exhaust 19.3 ∼ 19.5 mm (0.7598 ∼ 0.7677 in.)

○Measure the seat width [E] of the portion where there is

no build-up carbon (white portion) of the valve seat with a

vernier caliper.

Good [F]

If the width is too wide [G], too narrow [H] or uneven [J],

repair the seat (see Valve Seat Repair).

Valve Seating Surface Width

Standard:

Inlet, Exhaust

0.5 ∼ 1.0 mm (0.0197 ∼ 0.0394 in.)

Valve Seat Repair

• Repair the valve seat with the valve seat cutters [A].

Special Tools - Valve Seat Cutter Holder,

4.5: 57001-1330

[B]

Valve Seat Cutter Holder Bar: 57001-1128

[C]

For Inlet Valve Seat

Valve Seat Cutter, 45° -

24.5: 57001-1113

Valve Seat Cutter, 32° -

25: 57001-1118

Valve Seat Cutter, 67.5° -

22: 57001-1207

For Exhaust Valve Seat

Valve Seat Cutter, 45° -

24.5: 57001-1113

Valve Seat Cutter, 32° -

22: 57001-1206

Valve Seat Cutter, 67.5° -

22: 57001-1207

If the manufacturer’s instructions are not available, use

the following procedure.

ENGINE TOP END 5-29

Valves

Seat Cutter Operation Cares

1. This valve seat cutter is developed to grind the valve for

repair. Therefore the cutter must not be used for other

purposes than seat repair.

2. Do not drop or shock the valve seat cutter, or the dia-

mond particles may fall off.

3. Do not fail to apply engine oil to the valve seat cutter

before grinding the seat surface. Also wash off ground

particles sticking to the cutter with washing oil.

NOTE

○Do not use a wire brush to remove the metal particles

from the cutter. It will take off the diamond particles.

4. Setting the valve seat cutter holder in position, operate

the cutter in one hand. Do not apply too much force to

the diamond portion.

NOTE

○Prior to grinding, apply engine oil to the cutter and dur-

ing the operation, wash off any ground particles sticking

to the cutter with washing oil.

5. After use, wash it with washing oil and apply thin layer

of engine oil before storing.

Marks Stamped on the Cutter

The marks stamped on the back of the cutter [A] represent

the following.

60°

Cutter angle [B]

37.5

....................... Outer diameter of cutter [C]

Operating Procedures

• Clean the seat area carefully.

• Coat the seat with machinist’s dye.

• Fit a 45° cutter into the holder and slide it into the valve

guide.

• Press down lightly on the handle and turn it right or left.

Grind the seating surface only until it is smooth.

NOTICE

Do not grind the seat too much. Overgrinding will

reduce valve clearance by sinking the valve into the

head. If the valve sinks too far into the head, it will

be impossible to adjust the clearance, and the cylin-

der head must be replaced.

Widened Width [A] of engagement by machining with

45° cutter

Ground Volume [B] by 32° cutter

32° [C]

Correct Width [D]

Ground Volume [E] by 67.5° cutter

67.5° [F]

5-30 ENGINE TOP END

Valves

• Measure the outside diameter (O.D.) of the seating sur-

face with a vernier caliper.

If the outside diameter of the seating surface is too small,

repeat the 45° grind [A] until the diameter is within the

specified range.

Original Seating Surface [B]

NOTE

○Remove all pittings of flaws from 45° ground surface.

○After grinding with 45° cutter, apply thin coat of machin-

ist’s dye to seating surface. This makes seating surface

distinct and 32° and 67.5° grinding operation easier.

○When the valve guide is replaced, be sure to grind with

45° cutter for centering and good contact.

If the outside diameter of the seating surface is too large,

make the 32° grind described below.

• If the outside diameter [A] of the seating surface is within

the specified range, measure the seat width as described

below.

• Grind the seat at a 32° angle [B] until the seat O.D. is

within the specified range.

○To make the 32° grind, fit a 32° cutter into the holder, and

slide it into the valve guide.

○Turn the holder one turn at a time while pressing down

very lightly. Check the seat after each turn.

NOTICE

The

32° cutter removes material very quickly.

Check the seat outside diameter frequently to pre-

vent overgrinding.

○After making the 32° grind, return to the seat O.D. mea-

surement step above.

• To measure the seat width, use a vernier caliper to mea-

sure the width of the 45° angle portion of the seat at sev-

eral places around the seat.

If the seat width is too narrow, repeat the 45° grind until

the seat is slightly too wide, and then return to the seat

O.D. measurement step above.

If the seat width is too wide, make the 67.5° [A] grind

described below.

If the seat width is within the specified range, lap the valve

to the seat as described below.

• Grind the seat at a 67.5° angle until the seat width is within

the specified range.

○To make the 67.5° grind, fit a 67.5° cutter into the holder,

and slide it into the valve guide.

○Turn the holder, while pressing down lightly.

○After making the 67.5° grind, return to the seat width mea-

surement step above.

Correct Width [B]

ENGINE TOP END 5-31

Valves

• Lap the valve to the seat, once the seat width and O.D.

are within the ranges specified above.

○Put a little coarse grinding compound on the face of the

valve in a number of places around the valve head.

○Spin the valve against the seat until the grinding com-

pound produces a smooth, matched surface on both the

seat and the valve.

○Repeat the process with a fine grinding compound.

[A] Lapper

[B] Valve Seat

[C] Valve

• The seating area should be marked about in the middle

of the valve face.

If the seat area is not in the right place on the valve, check

to be sure the valve is the correct part. If it is, it may have

been refaced too much; replace it.

• Be sure to remove all grinding compound before assem-

bly.

• When the engine is assembled, be sure to adjust the valve

clearance (see Engine Top End in the Periodic Mainte-

nance chapter).

ENGINE TOP END 5-33

Cylinder, Pistons

Cylinder Removal

• Remove:

Cylinder Head (see Cylinder Head Removal)

• Loosen the clamps [A], and take off the water hose [B]

and pipe [C].

• Remove the cylinder [D].

Cylinder Installation

NOTE

○If a new cylinder is used, use a new piston ring.

• Install the dowel pins [A] and new cylinder gasket [B].

• Apply molybdenum disulfide oil solution to the cylinder

bore, piston rings and pistons.

• The piston ring openings must be positioned as shown in

the figure. The openings of the oil ring steel rails must be

about 30 ∼ 40° of angle from the opening of the top ring.

[A] Top Ring

[B] Second Ring

[C] Oil Ring Steel Rail (Upper)

[D] Oil Ring Steel Rail (Lower)

[E] Oil Ring Expander

[F] Arrow Mark

[G] 30 ∼ 40°

• Slip the piston base [A] as shown to hold piston level, and

install the cylinder.

Special Tool - Piston Base,

2.3: 57001-1336

5-34 ENGINE TOP END

Cylinder, Pistons

Piston Removal

• Remove the cylinder (see Cylinder Removal).

• Place a clean cloth under the pistons and remove the pis-

ton pin snap ring [A] from the outside of each piston.

• Remove the piston pins.

Special Tool - Piston Pin Puller Assembly: 57001-910 [A]

• Remove the pistons.

• Carefully spread the ring opening with your thumbs and

then push up on the opposite side of the ring [A] to remove

it.

• Remove the 3-piece oil ring with your thumbs in the same

manner.

Piston Installation

NOTE

○If a new piston is used, use a new piston ring.

• Install the piston with its marking dent facing forward.

• Fit a new piston pin snap ring into the side of the piston

so that the ring opening [A] does not coincide with the slit

[B] of the piston pin hole.

○When installing the piston pin snap ring, compress it only

enough to install it and no more.

NOTICE

Do not reuse snap rings, as removal weakens and

deforms them.

They could fall out and score the cylinder wall.

ENGINE TOP END 5-35

Cylinder, Pistons

• Install the oil ring expander [A] in the bottom piston ring

groove so the ends [B] butt together.

• Install the oil ring steel rails, one above the expander and

one below it.

○Spread the rail with your thumbs, but only enough to fit

the rail over the piston.

○Release the rail into the bottom piston ring groove.

NOTE

○The oil ring rails have no “top” or “bottom”.

• Do not mix up the top and second ring.

• Install the top ring [A] so that the “R” mark [B] faces up.

• Install the second ring [C] so that the “RN” mark [D] faces

up.

○Apply molybdenum disulfide oil solution to the piston

rings.

Cylinder Wear Inspection

• Since there is a difference in cylinder wear in different di-

rections, take a side-to-side and a front-to-back measure-

ment at each of the two locations (total of four measure-

ments) shown in the figure.

If any of the cylinder inside diameter measurements ex-

ceeds the service limit, replace the cylinder.

[A] 10 mm

[B] 60 mm

Cylinder Inside Diameter

Standard:

62.000 ∼ 62.012 mm (2.4409 ∼ 2.4414 in.)

Service Limit:

62.10 mm (2.44 in.)

Piston Wear Inspection

• Measure the outside diameter [A] of each piston 5 mm

(0.20 in.) [B] up from the bottom of the piston at a right

angle to the direction of the piston pin.

If the measurement is under service limit, replace the pis-

ton.

Piston Diameter

Standard:

61.942 ∼ 61.957 mm (2.4387 ∼ 2.4392 in.)

Service Limit:

61.80 mm (2.43 in.)

5-36 ENGINE TOP END

Cylinder, Pistons

Piston Ring, Piston Ring Groove Wear Inspection

• Check for uneven groove wear by inspecting the ring seat-

ing.

The rings should fit perfectly parallel to groove surfaces.

If not, replace the piston and all the piston rings.

• With the piston rings in their grooves, make several mea-

surements with a thickness gauge [A] to determine piston

ring/groove clearance.

Piston Ring/Groove Clearance

Standard:

Top

0.03 ∼ 0.07 mm (0.0012 ∼ 0.0028 in.)

Second

0.02 ∼ 0.06 mm (0.0008 ∼ 0.0024 in.)

Service Limit:

Top

0.17 mm (0.0067 in.)

Second

0.16 mm (0.0063 in.)

Piston Ring Groove Width Inspection

• Measure the piston ring groove width.

○Use a vernier caliper at several points around the piston.

Piston Ring/Groove Width

Standard:

Top

0.82 ∼ 0.84 mm (0.0323 ∼ 0.0331 in.)

Second

0.81 ∼ 0.83 mm (0.0319 ∼ 0.0327 in.)

Oil

1.51 ∼ 1.53 mm (0.0594 ∼ 0.0602 in.)

Service Limit:

Top

0.92 mm (0.0362 in.)

Second

0.91 mm (0.0358 in.)

Oil

1.61 mm (0.0634 in.)

If the width of any two grooves is wider than the service

limit at any point, replace the piston.

Piston Ring Thickness Inspection

• Measure the piston ring thickness.

○Use the micrometer to measure at several points around

the ring.

Piston Ring Thickness

Standard:

Top

0.77 ∼ 0.79 mm (0.0303 ∼ 0.0311 in.)

Second

0.77 ∼ 0.79 mm (0.0303 ∼ 0.0311 in.)

Service Limit:

Top

0.70 mm (0.028 in.)

Second

0.70 mm (0.028 in.)

If any of the measurements is less than the service limit

on either of the rings, replace all the rings.

NOTE

○When using new rings in a used piston, check for un-

even groove wear. The rings should fit perfectly parallel

to the groove sides. If not, replace the piston.

ENGINE TOP END 5-37

Cylinder, Pistons

Piston Ring End Gap Inspection

• Place the piston ring [A] inside the cylinder, using the pis-

ton to locate the ring squarely in place. Set it close to the

bottom of the cylinder, where cylinder wear is low.

• Measure the gap [B] between the ends of the ring with a

thickness gauge.

Piston Ring End Gap

Standard:

Top

0.15 ∼ 0.30 mm (0.0059 ∼ 0.0118 in.)

Second

0.40 ∼ 0.55 mm (0.0157 ∼ 0.0217 in.)

Oil

0.20 ∼ 0.80 mm (0.0079 ∼ 0.0315 in.)

Service Limit:

Top

0.6 mm (0.024 in.)

Second

0.9 mm (0.035 in.)

Oil

1.1 mm (0.043 in.)

If the end gap of either ring is greater than the service

limit, replace all the rings.

Boring, Honing

When boring and honing a cylinder, note the following:

○There is one size of oversize piston available. Oversize

piston require oversize rings.

Oversize Pistons and Rings

+0.5 mm (0.020 in.)

○Before boring a cylinder, first measure the exact diameter

of the oversize piston, and then, according to the stan-

dard clearance in the Specifications section, determine

the rebore diameter. However, if the amount of boring

necessary would make the inside diameter greater than

0.5 mm (0.002 in.) oversize, the cylinder block must be

replaced.

○Cylinder inside diameter must not vary more than 0.01

mm (0.0004 in.) at any point.

○Be wary of measurements taken immediately after boring

since the heat affects cylinder diameter.

○In the case of a rebored cylinder and oversize piston, the

service limit for the cylinder is the diameter that the cylin-

der was bored to plus 0.1 mm (0.004 in.) and the service

limit for the piston is the oversize piston original diameter

minus 0.15 mm (0.006 in.). If the exact figure for the re-

bored diameter is unknown, it can be roughly determined

by measuring the diameter at the base of the cylinder.

○Never separate the liner from the cylinder, because the

top surface of cylinder and liner is machined at the factory

as an assembly.

5-38 ENGINE TOP END

Carburetor Holder

Carburetor Holder Installation

• Install the carburetor holders [A] so that the “HEAD” marks

[B] faces forward (cylinder head side), and “CARB” mark

[C] faces backward (carburetor side).

• Install the holder clamps as shown being careful of the

screw [D] position and the screw head direction.

WARNING

Interference with the vacuum adjusting screws

can result in an unsafe riding condition and cause

a crash resulting in serious injury or death. In-

stall the clamp screws horizontally, otherwise the

screws could come in contact with vacuum adjust-

ing screws.

ENGINE TOP END 5-39

Muffler

Muffler Removal

• Remove:

Lower Fairings (see Lower Fairing Removal in the Frame

chapter)

• Remove:

Muffler Cover Bolts [A]

Muffler Cover Clamp Bolt [B]

Muffler Cover [C]

• Loosen the muffler clamp bolt [A] until the clamp turns

freely on the muffler.

• Remove the muffler mounting bolt [B] and nut at the rear

footpeg bracket, and take off the muffler.

• Remove the exhaust pipe holder nuts [A].

• Pull the exhaust pipe toward the front and remove it.

• Remove the gaskets from the exhaust pipe.

NOTICE

Be careful not to touch the radiator fins during

work. The fins are easily deformed.

Muffler Installation

• Smear a little grease on a new exhaust pipe gasket and

stick it into the exhaust port in the cylinder head.

• Attach the exhaust pipe loosely to the cylinder head.

○Position the exhaust pipe in the exhaust port.

• Install the gasket [A] so that its chamfer side [B] faces

manifold side.

Manifold Side [C]

Muffler Side [D]

• Slip the muffler into place from the rear of the frame so

that it fits over the exhaust pipe.

• Hold the muffler up and install the mounting bolts not to

tighten them securely.

• Tighten the exhaust pipe holder nuts evenly and securely.

• Tighten the muffler mounting bolt securely.

Torque - Exhaust Pipe Mounting Bolt: 9.8 N·m (1.0 kgf·m,

87 in·lb)

Exhaust Pipe Holder Nuts: 12 N·m (1.2 kgf·m, 104

in·lb)

Muffler Body Mounting Bolt: 30 N·m (3.1 kgf·m, 22

ft·lb)

5-40 ENGINE TOP END

Muffler

• Tighten the muffler clamp bolt [A] securely waving the di-

rection of the clamp bolts.

74° ∼ 84° [B]

Torque - Muffler Body Clamp Bolt: 17 N·m (1.7 kgf·m, 13

ft·lb)

○Be sure that the distance between the clamp bolt end and

the swingarm [C] is more than 15 mm [D].

• Insert the claw [A] into the cover clamp [B] and tighten the

clamp screw securely.

Torque - Muffler Cover Clamp Screw: 6.9 N·m (0.70 kgf·m,

61 in·lb)

Muffler Cover Bolts: 9.8 N·m (1.0 kgf·m, 87 in·lb)

○Be sure that the position of muffler cover clamp screw [A]

is as shown.

approx. 15° [B]

Exhaust System Inspection

• Before removing the exhaust system, check for signs of

leakage at the exhaust pipe gasket in the cylinder head

and at the muffler clamp.

If there are signs of leakage around the exhaust pipe gas-

ket, it should be replaced. If the muffler to exhaust pipe

joint leaks, tighten the clamp.

• Remove the exhaust system (see Muffler Removal).

• Inspect the gasket for damage and signs of leakage.

If the gasket is damaged or has been leaking, replace it.

• Check the exhaust pipe and muffler for dents, cracks, rust

and holes.

If the exhaust pipe or muffler is damaged or holes, it

should be replaced for best performance and least noise.

CLUTCH 6-1

Clutch

Table of Contents

Exploded View

6-2

Specifications

6-4

Special Tool and Sealant

6-5

Clutch Lever and Cable

6-6

Clutch Lever Free Play Inspection

6-6

Clutch Lever Free Play Adjustment

6-6

Clutch Cable Removal

6-6

Clutch Cable Lubrication

6-6

Clutch Lever Removal

6-6

Clutch Cover

6-7

Clutch Cover Removal

6-7

Clutch Cover Installation Note

6-7

Clutch Release Shaft Removal

6-7

Clutch Release Shaft Installation

6-7

Clutch

6-8

Clutch Removal

6-8

Clutch Installation

6-8

Clutch Plate Wear and Damage Inspection

6-9

Clutch Plate Warp Inspection

6-9

Clutch Spring Free Length Inspection

6-10

Clutch Housing Finger Damage Inspection

6-10

Clutch Hub Spline Damage Inspection

6-10

CLUTCH 6-3

Exploded View

Torque

No.

Fastener

Remarks

N·m

kgf·m

ft·lb

Clutch Lever Holder Clamp Bolts

8.8

0.9

78 in·lb

Clutch Spring Bolts

8.8

0.9

78 in·lb

Clutch Hub Nut

132

13.5

97.4

Oil Filler Plug

Hand-Tighten

Clutch Cover Bolts

9.8

1.0

87 in·lb

6. Starter Lockout Switch

7. Clutch Lever Pivot Nut

CL: Apply cable lubricant.

EO: Apply engine oil.

G: Apply grease.

M: Apply molybdenum disulfide grease.

R: Replacement Parts

Si: Apply silicone grease.

W: Apply water.

6-6 CLUTCH

Clutch Lever and Cable

Clutch Lever Free Play Inspection

• Refer to Clutch Operation Inspection in the Periodic Main-

tenance chapter (see Clutch Operation Inspection in the

Periodic Maintenance chapter).

Clutch Lever Free Play Adjustment

• Refer to Clutch Operation Inspection in the Periodic Main-

tenance chapter (see Clutch Operation Inspection in the

Periodic Maintenance chapter).

Clutch Cable Removal

• Remove:

Right Lower Fairing (see Lower Fairing Removal in the

Frame chapter)

• Loosen the knurled locknut [A] at the clutch lever, and

screw in the adjuster [B].

• Line up the slots [C] in the clutch lever, locknut, and ad-

juster and then free the cable from the lever.

• Remove the lower cable adjuster of clutch cable from the

cable holder [A] loosening the cable adjuster lock nuts [B].

• Free the clutch inner cable tip from the clutch release

lever.

Clutch Cable Lubrication

• Refer to Chassis Parts Lubrication in the Periodic Mainte-

nance chapter (see Chassis Parts Lubrication in the Pe-

riodic Maintenance chapter).

Clutch Lever Removal

• Remove the upper end of clutch cable.

• Remove the left switch housing [A].

• Remove the clutch lever mounting bolt [B] and nut, and

remove the clutch lever.

CLUTCH 6-7

Clutch Cover

Clutch Cover Removal

• Drain the engine oil (see Engine Oil Change in the Peri-

odic Maintenance chapter).

• Remove:

Right Lower Fairing (see Lower Fairing Removal in the

Frame chapter)

Clutch Cable (see Clutch Cable Removal)

Oil Filler Plug

• Remove the clutch cover mounting bolts [A] and the clutch

cable guide.

• Turn the clutch release lever couterclockwise fully to re-

lease the clutch release shaft.

Clutch Cover Installation Note

• Scrape the old gasket from the surface of clutch cover and

crankcase, and apply liquid gasket on the mating surface

[A] of the crankcases.

• Install the new clutch cover gasket.

Sealant - Liquid Gasket, TB1211F: 92104-0004

• Turn the clutch release lever [A] counterclockwise fully [B]

and install the clutch cover.

Clutch Release Shaft Removal

• Remove:

Clutch Cable (see Clutch Cable Removal)

Clutch Cover (see Clutch Cover Removal)

• Pull out the clutch release shaft from the clutch cover.

NOTE

○Do not damage the oil seal when it shall be inserted into

the clutch cover hole.

Clutch Release Shaft Installation

• Apply engine oil to the oil seal [A] and needle bearing [B].

• Insert the clutch release shaft into the clutch cover hole.

• Install:

Clutch Cover (see Clutch Cover Installation)

Clutch Cable (see Clutch Cable Installation)

NOTICE

When inserting the release shaft, be careful not to

remove the spring of the oil seal.

6-8 CLUTCH

Clutch

Clutch Removal

• Remove:

Clutch Cable (see Clutch Cable Removal)

Clutch Cover (see Clutch Cover Removal)

• Remove the clutch spring mounting bolts [A], springs,

clutch operating plate [B] with the clutch push rod [C].

• Remove the clutch steel plates and friction plates.

• Remove the clutch hub nut using the special tool [A].

• Remove the washer, clutch housing, needle bearing,

bushing and the thrust spacer.

Special Tool - Clutch Holder: 57001-1243

Clutch Installation

• Install the thrust spacer [A] so that the chamfer side of it

faces to inside of the engine.

• Install the spacer bushing [A] and needle bearing [B].

○Install the snap ring [C] on the bushing so that it faces to

inside of the engine.

• Install the clutch housing, clutch hub, washer and the

clutch hub nut.

• Tighten the clutch hub nut with the specified torque.

Special Tool - Clutch Holder: 57001-1243

Torque - Clutch Hub Nut: 132 N·m (13.5 kgf·m, 97.4 ft·lb)

CLUTCH 6-9

Clutch

• Install the friction plate first and clutch steel plate, and

afterward install them alternately.

○The outer-end [A] and inner-end [B] friction plate blocks

are wider than the others.

Wider [C]

Narrower [D]

• Install the clutch operating plate [A] with the clutch push

rod [B].

• Install the springs and tighten the clutch spring bolts with

specified torque.

Torque - Clutch Spring Bolts: 8.8 N·m (0.9 kgf·m, 78 in·lb)

• Install the clutch cover (see Clutch Cover Installation).

Clutch Plate Wear and Damage Inspection

• Visually inspect the friction and steel plates for signs of

seizure, overheating (discoloration), or uneven wear.

• Measure the thickness of each friction plate [A] at several

points.

If any plates show signs of damage, or if they have worn

past the service limit, replace them with new ones.

Friction Plate Thickness

Standard:

2.92 ∼ 3.08 mm (0.115 ∼ 0.121 in.)

Service Limit:

2.6 mm (0.10 in.)

Clutch Plate Warp Inspection

• Place each friction plate or steel plate on a surface plate

and measure the gap between the surface plate [A] and

each friction plate or steel plate [B] with a thickness gauge

[C]. The gap is the amount of friction or steel plate warp.

If any plate is warped over the service limit, replace it with

a new one.

Friction and Steel Plate Warp

Standard:

0.15 mm (0.0059 in.) or less

Service Limit:

0.3 mm (0.012 in.)

6-10 CLUTCH

Clutch

Clutch Spring Free Length Inspection

• Measure the free length of the clutch springs [A].

If any spring is shorter than the service limit, it must be

replaced.

Clutch Spring Free Length

Standard:

39.4 mm (1.55 in.)

Service Limit:

37.6 mm (1.48 in.)

Clutch Housing Finger Damage Inspection

• Visually inspect the clutch housing fingers [A] that come

in contact with the friction plate tangs.

If they are damaged or if there are groove cuts in the areas

that come in contact with the tangs, replace the housing.

Replace the friction plates if their tangs are damaged as

well.

Clutch Hub Spline Damage Inspection

• Visually inspect the areas of the clutch hub splines that

come in contact with the teeth of the steel plates.

If there are notches worn into the clutch hub splines [A],

replace the clutch hub. Replace the steel plates if their

teeth are damaged as well.

ENGINE LUBRICATION SYSTEM 7-1

Engine Lubrication System

Table of Contents

Exploded View

7-2

Specifications

7-4

Special Tools and Sealant

7-5

Engine Oil Flow Chart

7-6

Engine Oil and Oil Filter

7-7

Oil Level Inspection

7-7

Engine Oil Change

7-7

Oil Filter Replacement

7-7

Bypass Valve Disassembly

7-8

Bypass Valve Assembly

7-8

Bypass Valve Cleaning and Inspection

7-8

Oil Screen Cleaning and Inspection

7-9

Oil Pressure Relief Valve

7-10

Oil Pressure Relief Valve Removal

7-10

Oil Pressure Relief Valve Installation

7-10

Oil Pressure Relief Valve Inspection

7-10

Oil Pump

7-11

Oil Pump Removal

7-11

Oil Pump Installation

7-11

Oil Pump Disassembly

7-11

Oil Pump Assembly

7-11

Oil Pump Inspection

7-11

Oil Pressure Measurement

7-12

Oil Pressure Measurement

7-12

Oil Pressure Switch

7-13

Oil Pressure Switch Removal

7-13

Oil Pressure Switch Installation

7-13

ENGINE LUBRICATION SYSTEM 7-3

Exploded View

Torque

No.

Fastener

Remarks

N·m

kgf·m

ft·lb

Oil Hose Banjo Bolts

19.6

2.0

14.5

Oil Pressure Relief Valve

1.5

Crankcase Oil Passage Plug

1.5

Oil Passage Plugs for Oil Pump

2.0

Oil Pipe Banjo Bolt

1.2

104 in·lb

Oil Drain Bolt

19.6

2.0

14.5

Oil Pressure Switch

1.5

Oil Pressure Switch Terminal Bolt

1.5

0.15

13 in·lb

Oil Filter Mounting Bolt

19.6

2.0

14.5

Oil Breather Mounting Bolts

9.8

1.0

87 in·lb

Oil Pump Mounting Bolts

9.8

1.0

87 in·lb

Oil Screen Cover Bolts

9.8

1.0

87 in·lb

Plug

19.6

2.0

14.5

Breather Bolt

9.8

1.0

87 in·lb

EO: Apply engine oil.

G: Apply grease.

L: Apply a non-permanent locking agent.

R: Replacement Parts

SS: Apply silicone sealant.

7-4 ENGINE LUBRICATION SYSTEM

Specifications

Item

Standard

Engine Oil

Type

API SG, SH, SJ, SL or SM with JASO MA, MA1 or MA2

Viscosity

SAE 10W-40

Capacity

1.3 L (1.37 US qt) (when filter is not removed)

1.6 L (1.69 US qt) (when filter is removed)

1.7 L (1.80 US qt) (when engine is completely dry)

Oil Pressure Measurement

Oil Pressure @4 000 r/min (rpm), Oil

98 ∼ 147 kPa (1.0 ∼ 1.5 kgf/cm², 14 ∼ 21 psi)

Temperature 90°C (194°F)

ENGINE LUBRICATION SYSTEM 7-7

Engine Oil and Oil Filter

WARNING

Vehicle operation with insufficient, deteriorated,

or contaminated engine oil will cause accelerated

wear and may result in engine seizure, accident,

and injury. Check the oil level before each use and

change the oil and filter according to the periodic

maintenance chart.

Oil Level Inspection

• Check that the engine oil level is between the upper [A]

and lower [B] levels in the gauge.

If the oil level is too high, remove the excess oil, using a

syringe or some other suitable device.

If the oil level is too low, add the correct amount of oil

through the oil filler opening. Use the same type and

make of oil that is already in the engine.

NOTE

○Situate the motorcycle so that it is perpendicular to the

ground.

○If the motorcycle has just been used, wait several min-

utes for all the oil to drain down.

○If the oil has just been changed, start the engine and

run it for several minutes at idle speed. This fills the oil

filter with oil. Stop the engine, then wait several minutes

until the oil settles.

○If the engine oil type and make are unknown, use any

brand of the specified oil to top up the level in preference

to running the engine with the oil level low. Then at your

earliest convenience, change the oil completely.

NOTICE

Racing the engine before the oil reaches every part

can cause engine seizure.

If the engine oil gets extremely low or if the oil pump

or oil passages clog up or otherwise do not function

properly, the oil pressure warning light will light. If

this light stays on when the engine is running above

idle speed, stop the engine immediately and find the

cause.

Engine Oil Change

• Refer to Engine Oil Change in the Periodic Maintenance

chapter (see Engine Oil Change in the Periodic Mainte-

nance chapter).

Oil Filter Replacement

• Refer to Oil Filter Replacement in the Periodic Mainte-

nance chapter (see Oil Filter Replacement in the Periodic

Maintenance chapter).

7-8 ENGINE LUBRICATION SYSTEM

Engine Oil and Oil Filter

Bypass Valve Disassembly

• Remove the oil filter (see Oil Filter Replacement in the

Periodic Maintenance chapter).

NOTE

○Oil draining is not necessary, but place the oil pan un-

der the oil filter because oil drain a little at the oil filter

removal.

• Drive the retaining pin [A] out of the filter mounting bolt

[B].

• Drop out the spring [C] and the bypass valve steel ball [D].

Bypass Valve Assembly

• Drop the bypass valve steel ball into the filter mounting

bolt.

• Put the spring into the mounting bolt and compress it be-

yond the small hole.

• Drive the retaining pin into the small hole to hold the

spring.

• Install the oil filter (see Oil Filter Replacement in the Pe-

riodic Maintenance chapter).

Bypass Valve Cleaning and Inspection

• Disassemble the bypass valve (see Bypass Valve Disas-

sembly).

• Clean the bypass valve parts in a high-flash point solvent.

WARNING

Gasoline and low-flash point solvents can be

flammable and/or explosive and cause severe

burns. Clean the parts in a well ventilated area, and

take care that there is no spark or flame anywhere

near the working areas. Do not use gasoline or

low-flash point solvents to clean parts.

• Visually inspect the bypass valve parts.

If there is any damaged part, replace it.

ENGINE LUBRICATION SYSTEM 7-9

Engine Oil and Oil Filter

Oil Screen Cleaning and Inspection

• Remove the oil screen cover [A].

• Clean the oil screen [B] with high-flash point solvent and

remove any particles stuck to it.

WARNING

Gasoline and low-flash point solvents can be

flammable and/or explosive and cause severe

burns. Clean the screen in a well-ventilated area,

and take care that there are no sparks or flame

anywhere near the working area; this includes any

appliance with a pilot light. Do not use gasoline or

a low-flash point solvent to clean the screen.

NOTE

○While cleaning the screen, check for any metal particles

that might indicate internal engine damage.

• Check the screen carefully for any damage: holes and

broken wires.

If the screen is damaged, replace the oil screen.

7-10 ENGINE LUBRICATION SYSTEM

Oil Pressure Relief Valve

Oil Pressure Relief Valve Removal

• Remove the clutch cover (see Clutch Cover Removal in

the Clutch chapter).

• Unscrew the oil pressure relief valve [A] from the

crankcase.

Oil Pressure Relief Valve Installation

• Apply a non-permanent locking agent to the threads of

the relief valve, and tighten it with the specified torque.

Torque - Oil Pressure Relief Valve: 15 N·m (1.5 kgf·m, 11

ft·lb)

NOTICE

Do not over apply a non-permanent locking agent

to the threads. This may block the oil passage.

Oil Pressure Relief Valve Inspection

• Check to see if the valve [A] slides smoothly when push-

ing it in with a wooden or other soft rod, and see if it comes

back to its seat by spring [B] pressure.

NOTE

○Inspect the valve in its assembled state. Disassembly

and assembly may change the valve performance.

If any rough spots are found during above inspection,

wash the valve clean with a high-flash point solvent and

blow out any foreign particles that may be in the valve with

compressed air.

WARNING

Gasoline and low-flash point solvents can be

flammable and/or explosive and cause severe

burns. Clean the oil pressure relief valve in a

well-ventilated area, and take care that there are no

sparks or flame anywhere near the working area;

this includes any appliance with a pilot light. Do

not use gasoline or a low-flash point solvent to

clean the oil pressure relief valve.

If cleaning does not solve the problem, replace the oil

pressure relief valve as an assembly. The oil pressure

relief valve is precision made with no allowance for re-

placement of individual parts.

ENGINE LUBRICATION SYSTEM 7-11

Oil Pump

Oil Pump Removal

• Remove the clutch cover (see Clutch Cover Removal in

the Clutch chapter).

• Remove the clutch (see Clutch Removal in the Clutch

chapter).

• Remove the circlip and oil pump gear.

• Remove the oil pump mounting Allen bolts [A].

• Pull the oil pump [B] off the crankcase.

Oil Pump Installation

• Fill the oil pump with engine oil for initial lubrication.

• When installing the oil pump [A], note the position of the

water pump shaft slot [C] and turn the oil pump shaft so

that the projection [B] fits into the slot.

• Apply a non-permanent locking agent to the threads of the

oil pump mounting Allen bolts, and tighten them securely.

Torque - Oil Pump Mounting Bolts: 9.8 N·m (1.0 kgf·m, 87

in·lb)

Oil Pump Disassembly

• Remove the circlip [A] with circlip plire on the oil pump

shaft end.

Special Tool - Outside Circlip Pliers: 57001-144

• Take off the gear [B] from the shaft [C].

• Loosen the screws [D] before removing the oil pump

mounting bolts [E].

• Remove the oil pump (see Oil Pump Removal).

• Unscrew the oil pump cover screws [D] and take off the

cover [F].

• Pull the oil pump shaft [A], washer [B], pins [C], inner rotor

[D] and outer rotor [E] from the pump body [F].

Oil Pump Assembly

• Oil pump assembly is the reverse of disassembly.

• After completing the oil pump assembly, check that the

rotor shaft and rotor turn smoothly.

Oil Pump Inspection

• Disassemble the oil pump (see Oil Pump Disassembly).

• Visually inspect the oil pump body, inner and outer rotors

and covers.

If there is any damage or uneven wear, replace the oil

pump as an assembly.

7-12 ENGINE LUBRICATION SYSTEM

Oil Pressure Measurement

• Remove the right lower fairing (see Lower Fairing Re-

moval in the Frame chapter).

• Remove the oil passage plug, and attach the adapter [B]

and gauge [A] to the plug hole.

Special Tools - Oil Pressure Gauge, 10 kgf/cm²: 57001-164

Oil Pressure Gauge Adapter, M18 × 1.5:

57001-1278

• Start the engine and warm up the engine.

• Run the engine at the specified speed, and read the oil

pressure gauge.

If the oil pressure is much lower than the standard, check

the oil pump and oil pump relief valve.

If the reading is much higher than the standard, check the

oil passages for clogging.

Oil Pressure

Standard:

98 ∼ 147 kPa (1.0 ∼ 1.5 kgf/cm², 14 ∼ 21 psi)

@ 4 000 r/min (rpm), oil temperature 90°C

(194°F)

• Stop the engine.

• Remove the oil pressure gauge and adapter.

WARNING

Hot oil can cause severe burns. Beware of hot en-

gine oil that will drain through the oil passage when

the gauge adapter is removed.

ENGINE LUBRICATION SYSTEM 7-13

Oil Pressure Switch

Oil Pressure Switch Removal

• Remove:

Left Lower Fairing (see Lower Fairing Removal in the

Frame chapter)

Switch Cover [A]

Switch Terminal Bolt [B]

Oil Pressure Switch [C]

Oil Pressure Switch Installation

• Apply liquid gasket to the threads of the oil pressure

switch and tighten it.

Sealant - Liquid Gasket, TB1211: 56019-120

Torque - Oil Pressure Switch: 15 N·m (1.5 kgf·m, 11 ft·lb)

• Tighten the oil pressure switch terminal bolt.

Torque - Oil Pressure Switch Terminal Bolt: 1.5 N·m (0.15

kgf·m, 13 in·lb)

○Install the oil pressure switch lead [A] as shown.

45° [B]

Front [C]

• Apply grease to the terminal.

8-4 ENGINE REMOVAL/INSTALLATION

Engine Removal/Installation

Engine Removal

• Drain the engine oil (see Engine Oil Change in the Peri-

odic Maintenance chapter).

• Drain the coolant (see Coolant Change in the Periodic

Maintenance chapter).

• Remove:

Front Seat (see Front Seat Removal in the Frame chap-

ter)

Side Covers (see Side Cover Removal in the Frame

chapter)

Lower Fairings (see Lower Fairing Removal in the Frame

chapter)

Upper Fairings (see Upper Fairing Removal in the Frame

chapter)

Fuel Tank (see Fuel Tank Removal in the Fuel System

chapter)

Throttle Cable (see Throttle Cable Removal in the Fuel

System chapter)

Choke Cable (see Choke Cable Removal in the Fuel

System chapter)

Clutch Cable Lower End (see Clutch Cable Removal in

the Clutch chapter)

Muffler (see Muffler Removal in the Engine Top End

chapter)

Engine Sprocket (see Drive Chain Removal in the Final

Drive chapter)

• Remove:

Left Side Coolant Pipe [A]

Oil Pressure Switch Lead Connector [B]

Neutral Switch Terminal [C]

Breather Hose [D] at Air Cleaner Housing

Carburetor Holder Clamp (Loosen) [E]

Spark Plug Caps [F]

ENGINE REMOVAL/INSTALLATION 8-5

Engine Removal/Installation

• Remove or disconnect:

Cooling Hose [A] at Cylinder Head

Starter Motor Cable [B]

Engine Ground Terminal [C]

Alternator Lead Connector [D]

Crankshaft Sensor Lead Connector [E]

Air Suction Hose [F]

• Support the engine with a suitable stand [A].

• Remove the regulator/rectifier [A] and the engine mount-

ing bracket bolts and nuts.

• Remove:

Engine Mounting Bolts and Nuts [A]

Engine Assembly [B]

8-6 ENGINE REMOVAL/INSTALLATION

Engine Removal/Installation

Engine Installation

• Engine installation is the reverse of removal, and note the

following point.

○Insert the lower engine mounting bolt [A] first while sup-

porting the engine. Then insert the upper engine mount-

ing bolt [B], and tighten the nut loosely.

○Before tightening the mounting bolts, install the engine

brackets. When inserting the front engine mounting bolt,

use the suitable stand under the engine to lift it.

Torque - Engine Mounting Bracket Bolts, Nuts: 64 N·m (6.5

kgf·m, 47 ft·lb)

Engine Mounting Nuts: 64 N·m (6.5 kgf·m, 47 ft·lb)

○Run the wiring harness correctly (see Cable, Wire and

Hose Routing in the Appendix chapter).

○Adjust the following items after engine installation.

Throttle Cables (see Throttle Control System Inspection

in the Periodic Maintenance chapter)

Choke Cable (see Choke Cable Free Play Inspection in

the Fuel System chapter)

Clutch Cable (see Clutch Operation Inspection in the Pe-

riodic Maintenance chapter)

Drive Chain (see Drive Chain Slack Inspection in the

Periodic Maintenance chapter)

Carburetor Idling (see Idle Speed Inspection in the Peri-

odic Maintenance chapter)

• Fill the engine oil (see Engine Oil Change in the Periodic

Maintenance chapter).

• Fill the coolant (see Coolant Change in the Periodic Main-

tenance chapter).

CRANKSHAFT/TRANSMISSION 9-1

Crankshaft/Transmission

Table of Contents

Exploded View

9-2

Balancer

9-22

Specifications

9-6

Balancer Removal

9-22

Special Tools and Sealants

9-9

Balancer Installation

9-22

Crankcase

9-10

Balancer Shaft Bearing

Crankcase Splitting

9-10

Insert/Journal Wear Inspection .

9-22

Crankcase Assembly

9-11

Transmission

9-24

Crankcase Exchange

9-13

Shift Pedal Removal

9-24

Crankshaft and Connecting Rods

9-14

Shift Pedal Installation

9-24

Crankshaft Removal

9-14

External Shift Mechanism

Crankshaft Installation

9-14

Removal

9-25

Connecting Rod Removal

9-14

External Shift Mechanism

Connecting Rod Installation

9-15

Installation

9-25

Crankshaft/Connecting Rod

External Shift Mechanism

Cleaning

9-15

Inspection

9-26

Connecting Rod Bend Inspection

9-16

Transmission Removal

9-27

Connecting Rod Twist Inspection.

9-16

Transmission Installation

9-27

Connecting Rod Big End Side

Transmission Shaft Disassembly.

9-27

Clearance Inspection

9-16

Transmission Shaft Assembly

9-28

Connecting Rod Big End

Shift Drum and Fork Removal

9-29

Bearing Insert/Crankpin Wear

Shift Drum and Fork Installation...

9-30

Inspection

9-17

Shift Drum Disassembly

9-30

Crankshaft Side Clearance

Shift Drum Assembly

9-30

Inspection

9-18

Gear Backlash Inspection

9-31

Crankshaft Runout Inspection

9-19

Shift Fork Bending Inspection

9-31

Crankshaft Main Bearing

Shift Fork/Gear Groove Wear

Insert/Journal Wear Inspection .

9-19

Inspection

9-31

Starter Motor Clutch

9-21

Shift Fork Guide Pin/Drum

Starter Motor Clutch

Groove Wear Inspection

9-31

Removal/Installation

9-21

Gear Dog and Gear Dog Hole

Starter Motor Clutch Inspection ...

9-21

Damage Inspection

9-32

Starter Motor Clutch Disassembly

9-21

Ball and Needle Bearing Wear

Starter Motor Clutch Assembly

9-21

Inspection

9-32

CRANKSHAFT/TRANSMISSION 9-3

Exploded View

Torque

No.

Fastener

Remarks

N·m

kgf·m

ft·lb

Oil Breather Mounting Bolts

9.8

1.0

87 in·lb

Crankcase Bolts

1.2

104 in·lb

Crankcase Bolts

8 (L = 90)

2.4

MO, S

Crankcase Bolts

8 (L = 73)

1.9

MO, S

Starter Motor Clutch Bolts

34.3

3.5

Connecting Rod Big End Cap Nuts

27.5

2.8

Shift Drum Bearing Holder Bolt

1.2

104 in·lb

L: Apply a non-permanent locking agent.

LG: Apply liquid gasket.

M: Apply molybdenum disulfide grease.

MO: Apply molybdenum disulfide oil solution (mixture of the engine oil and molybdenum disulfide

grease in a weight ratio 10:1).

R: Replacement Parts

S: Follow the specified tightening sequence.

W: Washer

CRANKSHAFT/TRANSMISSION 9-5

Exploded View

Torque

No.

Fastener

Remarks

N·m

kgf·m

ft·lb

Shift Drum Pin Plate Bolt

9.0

0.9

80 in·lb

Neutral Switch

1.5

External Shift Mechanism Return Spring Pin

19.6

2.0

14.5

Shift Drum Positioning Bolt

24.5

2.5

Shift Lever Link Bolt

1.2

104 in·lb

Front Tie-Rod Locknut (Left-Hand Threads)

7.0

0.7

62 in·lb

Rear Tie-Rod Locknut (Right-Hand Threads)

7.0

0.7

62 in·lb

EX250J8 ∼ JB (with a non-permanent locking

agent)

2.0

Shift Pedal Mounting Bolt

EX250JB ∼ JC (with a non-permanent locking

agent)

2.5

Shift Pedal Mounting Bolt

EO: Apply engine oil.

G: Apply grease.

L: Apply a non-permanent locking agent.

R: Replacement Parts

9-6 CRANKSHAFT/TRANSMISSION

Specifications

Item

Standard

Service Limit

Crankshaft, Connecting Rods

Connecting Rod Bend

---

TIR 0.2/100 mm

(0.008/3.94 in.)

Connecting Rod Twist

---

TIR 0.2/100 mm

(0.008/3.94 in.)

Connecting Rod Big End Side Clearance

0.13 ∼ 0.38 mm

0.58 mm

(0.005 ∼ 0.015 in.)

(0.023 in.)

Connecting Rod Big End Bearing

0.031 ∼ 0.059 mm

0.10 mm

Insert/Crankpin Clearance

(0.0012 ∼ 0.0023 in.)

(0.004 in.)

Crankpin Diameter:

29.984 ∼ 30.000 mm

29.97 mm

(1.1805 ∼ 1.1811 in.)

(1.18 in.)

Marking

None

29.984 ∼ 29.994 mm

- - -

(1.1805 ∼ 1.1809 in.)

○

29.995 ∼ 30.000 mm

- - -

(1.1809 ∼ 1.1811 in.)

Connecting Rod Big End Bore Diameter:

33.000 ∼ 33.016 mm

- - -

(1.2992 ∼ 1.2998 in.)

Marking

None

33.000 ∼ 33.008 mm

- - -

(1.2992 ∼ 1.2995 in.)

○

33.009 ∼ 33.016 mm

- - -

(1.2996 ∼ 1.2998 in.)

Connecting Rod Big End Bearing Insert

Thickness:

Brown

1.480 ∼ 1.485 mm

- - -

(0.0583 ∼ 0.0585 in.)

Black

1.485 ∼ 1.490 mm

- - -

(0.0585 ∼ 0.0587 in.)

Blue

1.489 ∼ 1.494 mm

- - -

(0.0586 ∼ 0.0588 in.)

Crankshaft Runout

TIR 0.02 mm (0.0008 in.) or

TIR 0.05 mm

less

(0.0020 in.)

Crankshaft Main Bearing Insert/Journal

0.014 ∼ 0.038 mm*

0.07 mm

Clearance

(0.0006 ∼ 0.0015 in.)

(0.0028 in.)

Crankshaft Main Journal Diameter:

27.984 ∼ 28.000 mm

27.96 mm

(1.1017 ∼ 1.1024 in.)

(1.101 in.)

Marking

None

27.984 ∼ 27.992 mm

- - -

(1.1017 ∼ 1.1020 in.)

27.993 ∼ 28.000 mm

- - -

(1.1021 ∼ 1.1024 in.)

Crankcase Main Bearing Bore Diameter:

31.000 ∼ 31.016 mm

- - -

(1.2205 ∼ 1.2211 in.)

Marking

○

31.000 ∼ 31.008 mm

- - -

(1.2205 ∼ 1.2208 in.)

CRANKSHAFT/TRANSMISSION 9-7

Specifications

Item

Standard

Service Limit

None

31.009 ∼ 31.016 mm

- - -

(1.2208 ∼ 1.2211 in.)

Crankshaft Main Bearing Insert Thickness:

Black

1.495 ∼ 1.499 mm

- - -

(0.0589 ∼ 0.0590 in.)

Blue

1.499 ∼ 1.503 mm

- - -

(0.0590 ∼ 0.0592 in.)

Yellow

1.503 ∼ 1.507 mm

- - -

(0.0592 ∼ 0.0593 in.)

Crankshaft Side Clearance

0.05 ∼ 0.20 mm

0.40 mm

(0.002 ∼ 0.008 in.)

(0.016 in.)

Balancer

Balancer Shaft Bearing Insert/Journal

0.020 ∼ 0.044 mm

0.07 mm

Clearance

(0.0008 ∼ 0.0017 in.)

(0.0028 in.)

Balancer Shaft Journal Diameter:

25.984 ∼ 26.000 mm

25.96 mm

(1.0230 ∼ 1.0236 in.)

(1.022 in.)

Marking

None

25.984 ∼ 25.994 mm

- - -

(1.0230 ∼ 1.0234 in.)

○

25.995 ∼ 26.000 mm

- - -

(1.0234 ∼ 1.0236 in.)

Crankcase Balancer Shaft Bore Diameter:

29.000 ∼ 29.016 mm

- - -

(1.1417 ∼ 1.1424 in.)

Marking

○

29.000 ∼ 29.008 mm

- - -

(1.1417 ∼ 1.1420 in.)

None

29.009 ∼ 29.016 mm

- - -

(1.1421 ∼ 1.1424 in.)

Balancer Shaft Bearing Insert Thickness:

Brown

1.495 ∼ 1.499 mm

- - -

(0.0589 ∼ 0.0590 in.)

Black

1.499 ∼ 1.503 mm

- - -

(0.0590 ∼ 0.0592 in.)

Blue

1.503 ∼ 1.507 mm

- - -

(0.0592 ∼ 0.0593 in.)

Transmission

Gear Backlash

0 ∼ 0.17 mm

0.25 mm

(0 ∼ 0.0067 in.)

(0.010 in.)

Gear Shift Fork Groove Width

5.05 ∼ 5.15 mm

5.3 mm

(0.1988 ∼ 0.2028 in.)

(0.209 in.)

Shift Fork Ear Thickness

4.9 ∼ 5.0 mm

4.8 mm

(0.1929 ∼ 0.1969 in.)

(0.189 in.)

Shift Fork Guide Pin Diameter

5.9 ∼ 6.0 mm

5.8 mm

(0.2323 ∼ 0.2362 in.)

(0.228 in.)

Shift Drum Groove Width

6.05 ∼ 6.20 mm

6.3 mm

(0.2382 ∼ 0.2441 in.)

(0.248 in.)

*: Journal clearance less than 0.025 mm (0.0010 in.) can not be measured by plastigage, however,

using genuine parts maintains the minimum standard clearance.

9-8 CRANKSHAFT/TRANSMISSION

Specifications

Connecting Rod Big End Bearing Insert Selection

Con-rod Big End Bore

Crankpin Diameter

Bearing Insert

Diameter Marking

Marking

Size Color

Parts Number

○

Black

92028-1493

None

○

None

Blue

92028-1492

None

○

Brown

92028-1494

Crankshaft Main Bearing Insert Selection

Crankcase Main

Crankpin Main

Bearing Insert**

Bearing Bore

Journal Diameter

Size Color

Parts Number

Journal Nos.

Diameter Marking

Marking

92028-1487

1, 3

○

Black

92028-1490

92028-1582

1, 3

None

Yellow

92028-1586

○

None

92028-1486

1, 3

Blue

None

92028-1489

**: The bearing inserts for No.2 journal have an oil groove.

Balancer Shaft Bearing Insert Selection

Balancer Shaft

Crankcase Balancer

Bearing Insert

Journal Diameter

Shaft Bore Diameter

Size Color

Parts Number

Marking

○

Brown

92028-1424

○

None

Black

92028-1423

None

○

None

Blue

92028-1422

9-10 CRANKSHAFT/TRANSMISSION

Crankcase

Crankcase Splitting

• Remove the engine (see Engine Removal in the Engine

Removal/Installation chapter).

• Set the engine on a clean surface or, preferably mount it

on an engine stand to hold the engine steady while parts

are being removed.

• Remove the water pipe and hose (cylinder rearward).

NOTE

○If the engine is to be mounted on an engine stand, the

upper crankcase half bolts [A] shown must be removed

before mounting the engine.

Washer [B]

• Remove:

Alternator Cover (see Alternator Cover Removal in the

Electrical System chapter)

Water Pump, Hose and Pipe (see Water Pump Removal

in the Cooling System chapter)

Starter Motor Clutch Gear

Oil Pipe and Banjo Bolt

Starter Motor (see Starter Motor Removal in the Electri-

cal System chapter)

Oil Pump (see Oil Pump Removal in the Engine Lubri-

cation System chapter)

Cylinder Head Cover (see Cylinder Head Cover Re-

moval in the Engine Top End chapter)

Alternator Rotor (see Alternator Rotor Removal in the

Electrical System chapter)

One Way Clutch Gear

Oil Hose Banjo Bolt

Camshafts Chain Tensioner (see Camshafts Chain Ten-

sioner Removal in the Engine Top End chapter)

Clutch Cover (see Clutch Cover Removal in the Clutch

chapter)

Camshafts (see Camshaft Removal in the Engine Top

End chapter)

Cylinder Head (see Cylinder Head Removal in the En-

gine Top End chapter)

Cylinder (see Cylinder Removal in the Engine Top End

chapter)

Pistons (see Piston Removal in the Engine Top End

chapter)

CRANKSHAFT/TRANSMISSION 9-11

Crankcase

• Remove the clutch only if the transmission drive shaft as-

sembly is to be removed.

• Remove the oil pressure bolt [A] with the oil pressure

switch [B] and oil hose [C].

• Remove the neutral switch [D].

• Remove the upper crankcase half bolt (1) (3 were re-

moved just after engine removal).

• Turn the engine upside down.

• Remove the oil filter mounting bolt, oil filter, and large

O-ring.

• Remove the oil screen cover [A] and screen [B].

• Remove the 6 mm [A] and 8 mm [B] lower crankcase half

bolt, ply the point [C] shown to split the two crankcase

halves apart, and lift off the lower crankcase half.

Washer [D]

Crankcase Assembly

NOTE

○The upper/lower crankcase halves are machined at the

factory as an assembly, so the crankcase halves must

be replaced as a set.

• Assembly is the reverse of splitting. Be careful of the

following items.

○With a high flash-point solvent, clean off the mating sur-

face of the crankcase halves and wipe dry.

○When installing the output and drive shafts, the crankcase

set pins [A] must go into the holes in the needle bearing

outer races, and the set rings [B] must fit into the grooves

in the ball bearings.

9-12 CRANKSHAFT/TRANSMISSION

Crankcase

○When the oil pressure switch is installed, apply the liquid

gasket to the threads of the switch.

Sealant - Liquid Gasket, TB1211: 56019-120

NOTICE

Make sure the crankcase set pins are properly

aligned to avoid damage to the crankcases upon

installation.

Don’t use usual set pins because the set pins of

this model are different from usual pins. They are

hollow and also used to pass oil. If you use usual

pins by mistake, the engine always seized.

○Check that the knock pins (2) are in place.

○Apply a little engine oil to the transmission gears ball bear-

ings, shift drum, and crankshaft main bearing inserts.

• Apply liquid gasket to the mating surface of the lower

crankcase half.

Sealant - Liquid Gasket, TB1216B: 92104-1064 [A]

○After assembling the crankcase halves, wipe off excess

liquid gasket on the inside portion [B].

NOTICE

If liquid gasket adheres to any areas not indicated,

the engine oil passage may be obstructed, causing

engine seizure.

○Check to see that the shift drum is in the neutral position,

that is, the projection at operating plate is seen from neu-

tral switch hole at the upper crankcase half.

○When fitting the lower crankcase half on the upper

crankcase half, each shift fork must fit in its gear groove.

○Loosely tighten all lower crankcase half bolts to a snug fit.

CRANKSHAFT/TRANSMISSION 9-13

Crankcase

• Apply molybdenum disulfide oil solution to flange [A] and

the threads [B] of the M8 bolts which is tightening order is

[1 ∼ 8] only (see the next figure).

○Following the sequence numbers on the lower crankcase

half, tighten the 8 mm bolts [A] first to about one half of

the specified torque, and finally to the specified torque in

the same sequence.

○Replace the copper washer [C] with a new one.

○Tighten the 6 mm bolts [B] on the lower crankcase half to

the specified torque.

Torque - Crankcase Bolts (

8, L = 90):

First: 10 N·m (1.0 kgf·m, 89 in·lb)

Final: 24 N·m (2.4 kgf·m, 18 ft·lb)

Crankcase Bolts (

8, L = 73):

First: 10 N·m (1.0 kgf·m, 89 in·lb)

Final: 19 N·m (1.9 kgf·m, 14 ft·lb)

○Replace the copper washer [B] with a new one.

○Tighten the 6 mm bolts [A] on the upper crankcase half to

the specified torque.

Torque - Crankcase Bolts (

6): 12 N·m (1.2 kgf·m, 104 in·lb)

• After tightening all crankcase bolts, check the following

items.

○Drive shaft and output shaft turn freely.

○While spinning the output shaft, shift the transmission

smoothly from 1st to 6th gear, and back,

○Unless the output shaft is turning, the transmission cannot

be shifted to 2nd gear or other higher gear positions.

Crankcase Exchange

If the crankcase is damaged, replace it with a new one.

• Remove the crankcase parts from the damaged case, and

install it to the new case. Pay attention to the following

items.

○When installing the oil passage plug must be inserted as

shown.

[1] Lower Crankcase Half

[2] Oil Passage Pipe

[3] Press

[4] Small Hall (Up)

[5] Slit (Horizontal)

○Fit the oil passage O-ring on the breather body. Replace

the O-ring with new ones, if deteriorated or damage. The

flat side of the O-ring must face down.

○Apply a non-permanent locking agent to the threads of

the breather bolts, and tighten them.

9-14 CRANKSHAFT/TRANSMISSION

Crankshaft and Connecting Rods

Crankshaft Removal

• Split the crankcase (see Crankcase Splitting).

• Take the crankshaft out of the upper crankcase.

Crankshaft Installation

• Install the removed parts in reverse of removal.

NOTE

○If the crankshaft is replaced with a new one, refer to the

Connecting Rod Big End Bearing Insert Selection in the

specifications.

NOTICE

If the crankshaft, bearing inserts, or crankcase

halves are replaced with new ones, select the bear-

ing inserts and check clearance with a plastigage

(press gauge) before assembling engine to be sure

the correct bearing inserts are installed.

• Align the timing mark [C] on the balancer drive gear [A]

with the timing mark [C] on the balancer gear [B].

• Apply molybdenum disulfide oil solution to the crankshaft

main bearing inserts.

• Install the crankshaft.

Connecting Rod Removal

• Split the crankcase (see Crankcase Splitting).

• Remove the connecting rod big end cap nuts.

• Remove the crankshaft.

NOTE

○Mark and record the locations of the connecting rods

and their big end caps so that they can be reassembled

in their original positions.

• Remove the connecting rods from the crankshaft.

NOTICE

Discard the connecting rod bolts. To prevent dam-

age to the crankpin surfaces, do not allow the con-

necting rod bolts to bump against the crankpins.

CRANKSHAFT/TRANSMISSION 9-15

Crankshaft and Connecting Rods

Connecting Rod Installation

NOTICE

To minimize vibration, the connecting rods should

have the same weight mark.

Big End Cap [A]

Connecting Rod [B]

Weight Mark, Alphabet [C]

Diameter Mark (Around Weight Mark) [D]: “○” or no

mark

NOTICE

If the connecting rods, big end bearing inserts, or

crankshaft are replaced with new ones, select the

bearing insert and check clearance with a plasti-

gage (press gauge) before assembling engine to be

sure the correct bearing inserts are installed.

NOTICE

The connecting rod bolts are designed to stretch

when tightened. Never reuse them.

• Replace the connecting rod big end bolts and nuts with

new ones.

• Apply molybdenum disulfide oil solution to the inner sur-

face of upper and lower bearing inserts [A].

• Apply molybdenum disulfide oil solution to the threads [B]

and seating surface [C] of the connecting rod nuts.

Torque - Connecting Rod Big End Cap Nuts: 27.5 N·m (2.8

kgf·m, 20 ft·lb)

Crankshaft/Connecting Rod Cleaning

• After removing the connecting rods from the crankshaft,

clean them with a high-flash point solvent.

• Blow the crankshaft oil passages with compressed air to

remove any foreign particles or residue that may have

accumulated in the passages.

9-16 CRANKSHAFT/TRANSMISSION

Crankshaft and Connecting Rods

Connecting Rod Bend Inspection

• Remove the connecting rod big end bearing inserts, and

reinstall the connecting rod big end cap.

• Select an arbor [A] of the same diameter as the connect-

ing rod big end, and insert the arbor through the connect-

ing rod big end.

• Select an arbor of the same diameter as the piston pin

and at least 100 mm (3.94 in.) long, and insert the arbor

[B] through the connecting rod small end.

• On a surface plate, set the big-end arbor on V block [C].

• With the connecting rod held vertically, use a height

gauge to measure the difference in the height of the

arbor above the surface plate over a 100 mm (3.94 in.)

length to determine the amount of connecting rod bend.

If the connecting rod bend exceeds the service limit, the

connecting rod must be replaced.

Connecting Rod Bend

Service Limit: TIR 0.2/100 mm (0.008/3.94 in.)

Connecting Rod Twist Inspection

• With the big-end arbor [A] still on V block [C], hold the

connecting rod horizontally and measure the amount that

the arbor [B] varies from being paralleled with the surface

plate over a 100 mm (3.94 in.) length of the arbor to de-

termine the amount of connecting rod twist.

If the connecting rod twist exceeds the service limit, the

connecting rod must be replaced.

Connecting Rod Twist

Service Limit: TIR 0.2/100 mm (0.008/3.94 in.)

Connecting Rod Big End Side Clearance

Inspection

• Measure the connecting rod big end side clearance [A].

○Insert a thickness gauge [B] between the big end and the

crank web to determine clearance.

Connecting Rod Big End Side Clearance

Standard:

0.13 ∼ 0.38 mm (0.005 ∼ 0.015 in.)

Service Limit: 0.58 mm (0.023 in.)

If the clearance exceeds the service limit, replace the con-

necting rod with new one and then check the clearance

again. If the clearance is too large after connecting rod

replacement, the crankshaft also must be replaced.

CRANKSHAFT/TRANSMISSION 9-17

Crankshaft and Connecting Rods

Connecting Rod Big End Bearing Insert/Crankpin

Wear Inspection

• Measure the bearing insert/crankpin clearance [B] with

plastigage [A].

• Tighten the big end nuts to the specified torque (see Con-

necting Rod Installation).

NOTE

○Do not move the connecting rod and crankshaft during

clearance measurement.

Connecting Rod Big End Bearing Insert/Crankpin

Clearance

Standard:

0.031 ∼ 0.059 mm (0.0012 ∼ 0.0023 in.)

Service Limit: 0.10 mm (0.004 in.)

If the clearance is within the standard, no bearing replace-

ment is required.

If the clearance is between 0.059 mm (0.0023 in.) and

the service limit 0.10 mm (0.004 in.), replace the bear-

ing inserts [A] with inserts painted black [B]. Check the

insert/crankpin clearance with the plastigage. The clear-

ance may exceed the standard slightly, but it must not be

less than the minimum in order to avoid bearing seizure.

If the clearance exceeds the service limit, measure the

diameter of the crankpins.

Crankpin Diameter

Standard:

29.984 ∼ 30.000 mm (1.1805 ∼ 1.1811 in.)

Service Limit: 29.97 mm (1.18 in.)

If any crankpin has worn past the service limit, replace the

crankshaft with a new one.

If the measured crankpin diameters are not less than the

service limit, but do not coincide with the original diameter

markings on the crankshaft, make new marks on it.

Crankpin Diameter Marks

None: 29.984 ∼ 29.994 mm (1.1805 ∼ 1.1809 in.)

○:

29.995 ∼ 30.000 mm (1.1809 ∼ 1.1811 in.)

◊: Crankpin Diameter Marks, "○" mark or no mark.

9-18 CRANKSHAFT/TRANSMISSION

Crankshaft and Connecting Rods

• Measure the connecting rod big end bore diameter, and

mark each connecting rod big end in accordance with the

bore diameter.

• Tighten the big end nuts to the specified torque (see Con-

necting Rod Installation).

NOTE

○The mark already on the big end should almost coincide

with the measurement because of little wear.

Connecting Rod Big End Bore Diameter Marks

None: 33.000 ∼ 33.008 mm (1.2992 ∼ 1.2995 in.)

○:

33.009 ∼ 33.016 mm (1.2996 ∼ 1.2998 in.)

Big End Cap [A]

Connecting Rod [B]

Weight Mark, Alphabet [C]

Diameter Mark (Around Weight Mark) [D]: “○” or no

mark

• Select the proper bearing insert [A] in accordance with the

combination of the connecting rod and crankshaft coding.

Size Color [B]

Con-rod Bid

Crankpin

Bearing Insert

End Bore

Diameter

Size Color

Part Number

Diameter

Marking

None

○

Brown

92028-1494

None

Black

92028-1493

○

None

Blue

92028-1492

• Install the new inserts in the connecting rod and check

insert/crankpin clearance with the plastigage.

Crankshaft Side Clearance Inspection

• Insert a thickness gauge [A] between the crankcase main

bearing and the crank web at the No. 2 journal [B] to

determine clearance.

If the clearance exceeds the service limit, replace the

crankcase halves as a set.

NOTE

○The upper and lower crankcase halves are machined

at the factory in the assembled state, so the crankcase

halves must be replaced as a set.

Crankshaft Side Clearance

Standard:

0.05 ∼ 0.20 mm (0.002 ∼ 0.008 in.)

Service Limit:

0.40 mm (0.016 in.)

CRANKSHAFT/TRANSMISSION 9-19

Crankshaft and Connecting Rods

Crankshaft Runout Inspection

• Measure the crankshaft runout.

If the measurement exceeds the service limit, replace the

crankshaft.

Crankshaft Runout

Standard:

TIR 0.02 mm (0.0008 in.) or less

Service Limit: TIR 0.05 mm (0.002 in.)

Crankshaft Main Bearing Insert/Journal Wear

Inspection

• Using a plastigage (press gauge), measure the bearing

insert/journal [B] clearance [A].

NOTE

○Tighten the crankcase bolts to the specified torque (see

Crankcase Assembly).

○Do not turn the crankshaft during clearance measure-

ment.

○Journal clearance less than 0.025 mm (0.001 in.) can

not be measured by plastigage, however, using genuine

parts maintains the minimum standard clearance.

Crankshaft Main Bearing Insert/Journal Clearance

Standard:

0.014 ∼ 0.038 mm (0.0006 ∼ 0.0015 in.)

Service Limit: 0.07 mm (0.0028 in.)

If the clearance is within the standard, no bearing replace-

ment is required.

If the clearance is between 0.038 mm (0.0015 in.) and the

service limit 0.07 mm (0.0028 in.), replace the bearing in-

serts [A] with inserts painted blue [B]. Check insert/journal

clearance with the plastigage. The clearance may exceed

the standard slightly, but it must not be less than the min-

imum in order to avoid bearing seizure.

If the clearance exceeds the service limit, measure the

diameter of the crankshaft main journal.

Crankshaft Main Journal Diameter

Standard:

27.984 ∼ 28.000 mm (1.1017 ∼ 1.1024 in.)

Service Limit: 27.96 mm (1.101 in.)

If any journal has worn past the service limit, replace the

crankshaft with a new one.

If the measured journal diameters are not less than the

service limit, but do not coincide with the original diameter

markings on the crankshaft, make new marks on it.

Crankshaft Main Journal Diameter Marks

None: 27.984 ∼ 27.992 mm (1.1017 ∼ 1.1020 in.)

27.993 ∼ 28.000 mm (1.1021 ∼ 1.1024 in.)

□: Crankshaft Main Journal Diameter Marks, "1" mark

or no mark.

9-20 CRANKSHAFT/TRANSMISSION

Crankshaft and Connecting Rods

• Measure the main bearing bore diameter, and mark the

upper crankcase half in accordance with the bore diame-

ter.

A: Crankcase Main Bearing Bore Diameter Marks, "○"

mark or no mark.

NOTE

○Tighten the crankcase bolts to the specified torque (see

Crankcase Assembly).

○The mark already on the upper crankcase half should

almost coincide with the measurement.

Crankcase Main Bearing Bore Diameter Marks

○:

31.000 ∼ 31.008 mm (1.2205 ∼ 1.2208 in.)

None: 31.009 ∼ 31.016 mm (1.2208 ∼ 1.2211 in.)

• Select the proper bearing insert [A] in accordance with the

combination of the crankcase and crankshaft coding.

Size Color [B]

Crankcase Main

Crankshaft Main

Bearing Insert*

Bearing Bore

Journal Diameter

Size Color

Part Number

Journal Nos.

Diameter Marking

Marking

92028-1487

1, 3

○

Black

92028-1490

None

92028-1486

1, 3

Blue

○

None

92028-1489

92028-1582

1, 3

None

Yellow

92028-1586

*The bearing insert for No.2 journal have an oil groove.

• Install the new inserts in the crankcase halves and check

insert/journal clearance with the plastigage.

CRANKSHAFT/TRANSMISSION 9-21

Starter Motor Clutch

Starter Motor Clutch Removal/Installation

• Refer to Alternator Rotor Removal and Installation in the

Electrical System chapter (see Alternator Rotor Removal

and Installation in the Electrical System chapter).

Starter Motor Clutch Inspection

• Remove:

Alternator Cover (see Alternator Cover Removal in the

Electrical System chapter)

Starter Idle Gear

• Turn the starter motor clutch gear [A] by hand. The starter

motor clutch gear should turn clockwise [B] freely, but

should not turn counterclockwise [C].

If the starter motor clutch does not operate as it should or

if it makes noise, go to the next step.

• Disassemble the starter motor clutch, and visually inspect

the clutch parts.

If there is any worn or damaged part, replace it.

NOTE

○Examine the starter motor clutch gear as well. Replace

it if is worn or damage.

Starter Motor Clutch Disassembly

• Remove:

Alternator Rotor (see Alternator Rotor Removal in the

Electrical System chapter)

Starter Motor Clutch Bolts [A] and Starter Motor Clutch

[B]

Alternator Rotor [C]

Starter Motor Clutch Assembly

• Apply a non-permanent locking agent to the threads of

the starter motor clutch bolts and tighten them.

Torque - Starter Motor Clutch Bolts: 34.3 N·m (3.5 kgf·m,

25 ft·lb)

9-22 CRANKSHAFT/TRANSMISSION

Balancer

Balancer Removal

• Split the crankcase (see Crankcase Splitting).

• Pull the balancer shaft with the balancer gear out of the

crankcase.

Balancer Installation

• Balancer installation is the reverse of removal.

• Apply oil to the inside of the balancer shaft bearing insert.

• Align the timing mark [C] on the balancer gear [B] with

the timing mark [C] on the balancer drive gear [A] of the

crankshaft.

Balancer Shaft Bearing Insert/Journal Wear

Inspection

• Measure the bearing insert/journal clearance.

○Split the crankcase and wipe each bearing insert and jour-

nal [A] surface clean of oil.

○Cut strips of plastigage (press gauge) [B] to bearing insert

width, and place a strip on each journal parallel to the

balancer shaft so that the plastigage will be compressed

between the journal and the bearing insert.

○Install the lower crankcase half, and tighten the case bolts

to the specified torque.

Torque - Crankcase Bolts

8: 27 N·m (2.8 kgf·m, 20 ft·lb)

Crankcase Bolts

6: 12 N·m (1.2 kgf·m, 104 in·lb)

NOTE

○Do not turn the balancer shaft during clearance mea-

surement.

○Remove the lower crankcase half and measure the plas-

tigage width to determine the bearing insert/journal clear-

ance.

Balancer Shaft Bearing Insert/Journal Clearance

Standard:

0.020 ∼ 0.044 mm (0.0008 ∼ 0.0017 in.)

Service Limit: 0.07 mm (0.0028 in.)

If the clearance is within the standard, no bearing replace-

ment is required.

If the clearance is between 0.044 mm (0.0017 in.) and

the service limit 0.07 mm (0.0028 in.), replace the bear-

ing inserts with inserts painted blue. Check insert/journal

clearance with the plastigage. The clearance may exceed

the standard slightly, but it must not be less than the min-

imum in order to avoid bearing seizure.

If the clearance exceeds the service limit, measure the

diameter of the balancer shaft journal.

Balancer Shaft Journal Diameter

Standard:

25.984 ∼ 26.000 mm (1.0230 ∼ 1.0236 in.)

Service Limit:

25.96 mm (1.022 in.)

CRANKSHAFT/TRANSMISSION 9-23

Balancer

If either journal has worn past the service limit, replace

the balancer shaft with a new one.

If the measured journal diameter is not less than the ser-

vice limit, but does not coincide with the original diameter

markings [A] on the balancer shaft, make new marks on

it.

Balancer Shaft Journal Diameter Marks

None: 25.984 ∼ 25.994 mm (1.0230 ∼ 1.0234 in.)

○:

25.995 ∼ 26.000 mm (1.0234 ∼ 1.0236 in.)

• Put the lower crankcase half on the upper crankcase half

without bearing inserts, and tighten the case bolts to the

specified torque and sequence (see Crankcase Assem-

bly).

• Measure the main bearing inside diameter, and mark the

upper crankcase half in accordance with the inside diam-

eter.

NOTE

○The mark [A] already on the upper crankcase half

should almost coincide with the measurement.

Crankcase Bearing Inside Diameter Marks

○:

29.000 ∼ 29.008 mm (1.1417 ∼ 1.1420 in.)

None: 29.009 ∼ 29.016 mm (1.1421 ∼ 1.1424 in.)

• Select the proper bearing inserts [A] in accordance with

the combination of the crankcase and balancer shaft cod-

ing.

• Install the new inserts in the crankcase and check in-

sert/journal clearance with the plastigage.

Size Color [B]

Crankcase

Balancer

Bearing Insert

Bearing Inside

Shaft Journal

Part Number

Diameter Mark

Diameter MarkSizeColor

○

Brown

92028-1424

None

Blue

92028-1422

○

None

Black

92028-1423

None

○

9-24 CRANKSHAFT/TRANSMISSION

Transmission

Shift Pedal Removal

• Remove:

Shift Pedal Mounting Bolt [A]

Shift Lever Bolt [B]

Shift Pedal [C] with Shift Lever

Shift Pedal Installation

• Apply grease to the shift pedal [A].

• Install the washers [B] and shift pedal.

• For EX250J8 ∼ JB (with a non-permanent locking agent)

models, apply a non-permanent locking agent to the shift

pedal mounting bolt [C], and tighten it.

Torque - Shift Pedal Mounting Bolt: 20 N·m (2.0 kgf·m, 15

ft·lb)

• For EX250JB ∼ JC (without a non-permanent locking

agent) models, tighten the shift pedal mounting bolt.

Torque - Shift Pedal Mounting Bolt: 25 N·m (2.5 kgf·m, 18

ft·lb)

• Align the mark [A] on the shift shaft with the mark [B] on

the shift lever.

• Tighten:

Torque - Shift Lever Link Bolt: 12 N·m (1.2 kgf·m, 106 in·lb)

• Install the shift pedal [C] as shown in the figure.

About 16° [D]

○To adjust the pedal position, loosen the front locknut [E]

(left-hand threads) and rear locknut [F] and then turn the

tie-rod [G].

• Tighten:

Torque - Tie-Rod Locknuts: 7.0 N·m (0.71 kgf·m, 62 in·lb)

CRANKSHAFT/TRANSMISSION 9-25

Transmission

• Be sure the sealing lip of the rubber boots [A] fits into the

groove of the ball joint after installing the shift lever link.

Correctly Boot Fitting Position [B]

Incorrectly Boot Fitting Position [C]

External Shift Mechanism Removal

• Drain the engine oil (see Engine Oil Change in the Peri-

odic Maintenance chapter).

• Remove the shift lever link bolt [A] and pull the lever link

off the shift shaft end.

• Remove the clutch (see Clutch Removal in the Clutch

chapter).

• Move the shift mechanism arm [A] and over shift limiter

[B] out of their positions on the end of the shift drum [C],

and pull out the shift shaft [D] with the arm, pawl spring

[E] and return spring [F].

External Shift Mechanism Installation

• Check that the return spring [A] and pawl spring [B] are

properly fitted on the mechanism, install the external shift

mechanism, and place the shift mechanism arm [C] and

over shift limiter [D] on the shift drum pins.

• Add the engine oil (see Lubrication System in the Periodic

Maintenance chapter).

9-26 CRANKSHAFT/TRANSMISSION

Transmission

• Be sure the sealing lip of the rubber boot [A] fits into the

groove of the ball joint after installing the shift lever link.

○Correctly Boot Fitting Position [A]

○Incorrectly Boot Position [B]

• Align the mark [A] on the shift shaft with the mark [B] on

the shift lever link.

• Position the shift lever [C] as shown.

Approx. 15° [D]

External Shift Mechanism Inspection

• Examine the shift shaft for any damage.

If the shift shaft [A] is bent, straighten or replace it.

If the splines [B] are damaged, replace the shaft.

If the return spring [C] or pawl spring [D] is broken or dis-

torted, replace them.

If the shift mechanism arm [E] or over shift limiter [F] is

distorted, replace the shift shaft.

• Check the return spring pin is not loose.

If it is loose, unscrew it and apply a non-permanent lock-

ing agent to the threads, and tighten it.

Torque - External Shift Mechanism Return Spring Pin: 19.6

N·m (2.0 kgf·m, 14.5 ft·lb)

CRANKSHAFT/TRANSMISSION 9-27

Transmission

• Visually inspect the shift drum pins [A], pin holder [B] and

pin plate [C].

If they are badly worn or if they show any damage, replace

them.

Transmission Removal

• Split the crankcase (see Crankcase Splitting).

• Remove the drive shaft [A] and output shaft [B].

Transmission Installation

• With a high flash-point solvent, clean off the outer cir-

cumferences of the transmission ball bearings and needle

bearing housings, and wipe dry.

• Check to see that the set rings [A] and set pins [B] are

in place in the transmission bearing housings clean with

compressed air.

• Install the drive shaft and output shaft into the upper

crankcase half.

• Apply engine oil to the sliding surfaces of the gears and

bearings.

○The bearing set pins and rings must match properly with

the holes or grooves in the bearing outer races. When

they are properly matched, there is no clearance between

the crankcase [A] and the bearing outer races [B].

• Assemble the crankcase.

Transmission Shaft Disassembly

• Remove the transmission shafts (see Transmission Shaft

Removal).

• Remove the circlips, disassemble the transmission

shafts.

Special Tool - Outside Circlip Pliers: 57001-144

• The 5th gear [A] on the output shaft has three steel balls

assembled into it for the positive neutral finder mecha-

nism. Remove the 5th gear.

○Set the output shaft in a vertical position holding the 3rd

gear [C].

○Spin the 5th gear quickly [B] and pull it off upward.

9-28 CRANKSHAFT/TRANSMISSION

Transmission

• Remove the ball bearing [A] from each shafts.

Special Tools - Bearing Puller: 57001-135 [B]

Bearing Puller Adapter: 57001-317 [C]

• Discard the bearing.

Transmission Shaft Assembly

• Install the ball bearing on the drive shaft with the groove

toward the clutch side.

• Install the gear bushing [A] on the shafts with their oil

holes [B] aligned.

• The drive shaft gears can be recognized by size: the gear

with the smallest diameter is 1st gear, and the largest one

is 6th gear. Be sure that all parts are put back in the cor-

rect sequence and all circlips and washers are properly in

place.

• The output shaft gears can be recognized by size: the

gear with the largest diameter is 1st gear, and the small-

est one is 6th gear. Be sure that all parts are put back

in the correct sequence and all circlips and washers are

properly in place.

• Fit the steel balls into the 5th gear holes in the output shaft

as shown.

View A - A’ (see CRANKSHAFT/TRANSMISSION 9-33)

5th Gear [A]

Output Shaft [B]

Steel Balls [C]

Oil Hole [D]

NOTICE

Do not apply grease to the steel balls to hold them

in place. This will cause the positive neutral finder

mechanism to malfunction.

○Check the ball-locking effect that the 5th gear does not

come out of the output shaft when moving it up and down

by hand.

CRANKSHAFT/TRANSMISSION 9-29

Transmission

• Replace any circlip that were removed with new ones.

• Install the circlips [A] so that opening [B] is aligned with a

spline groove [C].

• Check that each gear spins or slides freely on the trans-

mission shafts without binding after assembly.

Shift Drum and Fork Removal

• Split the crankcase (see Crankcase Splitting).

• Remove the neutral positioning bolt [A] and take off

the washer [B], spring [C] and pin [D] from the upper

crankcase half [E].

• Remove the shift drum bearing holder bolts [A] and take

the holder plate [D] out of the shift drum [B] and shift rod

[C].

• Pull the shift rods [A] off the right side of the upper

crankcase half, and take off the drive shaft shift fork [B]

and the output shaft shift forks [C].

• Pull out the shift drum [A] about half of it, and remove the

circlip [B] and the operating plate [C].

• Pull out the shift drum fully from the upper crankcase.

9-30 CRANKSHAFT/TRANSMISSION

Transmission

Shift Drum and Fork Installation

• Set the transmission gear in the neutral position.

• Insert the shift drum into the upper crankcase half, and

install the operating plate pin [A], operating plate [B] and

circlip [C].

NOTE

○When installing the operating plate the projection [D]

faces toward the outside.

• Apply a little engine oil to the shift rods and shift fork fin-

gers.

• Insert the shift rods [D] running them through the shift

forks, fitting each shift fork guide pin into the shift drum

grooves.

○Position the one with shortest ear [A] on the drive shaft

and place the guide pin in the center groove in the shift

drum [B].

○The two forks [C] on the output shaft are identical.

• Install the shift drum bearing holder plate [A].

○Apply a non-permanent locking agent to the threads of

the shift drum bearing holder bolts [B], and tighten them

with the specified torque.

Torque - Shift Drum Bearing Holder Bolts:

12 N·m (1.2

kgf·m, 104 in·lb)

• Install the neutral positioning bolt with the specified torque

to the upper crankcase.

Torque - Shift Drum Positioning Bolt: 24.5 N·m (2.5 kgf·m,

18 ft·lb)

Shift Drum Disassembly

• Remove the shift drum (see Shift Drum Removal).

• When holding the shift drum with a vise, remove the shift

drum pin plate bolt.

Shift Drum Assembly

• Be sure to install the dowel pin [F].

• The shift drum pins [C] are identical.

• Apply a non-permanent locking agent to the threads of

the shift drum pin plate bolt [A], and tighten it.

Torque - Shift Drum Pin Plate Bolt: 9.0 N·m (0.9 kgf·m, 80

in·lb)

Shift Drum Pin Plate [B]

Shift Drum Bearing Holder [D]

Shift Drum Bearing [E]

Shift Drum [G]

Operating Plate Pin [H]

Operating Plate [I]

Circlip [J]

CRANKSHAFT/TRANSMISSION 9-31

Transmission

Gear Backlash Inspection

• Split the crankcase leaving the transmission in place.

• Set a dial gauge against the teeth on one gear, and move

the gear back and forth [A] while holding the other gear

steady [B]. The difference between the highest and the

lowest gauge readings is the amount of backlash.

Replace both gears if the amount of backlash exceeds

the service limit.

Gear Backlash

Standard:

0 ∼ 0.17 mm (0 ∼ 0.0067 in.)

Service Limit: 0.25 mm (0.010 in.)

Shift Fork Bending Inspection

• Visually inspect the shift forks, and replace any fork that is

bent. A bent fork could cause difficulty in shifting, or allow

the transmission to jump out of gear when under power.

90° [A]

Shift Fork/Gear Groove Wear Inspection

• Measure the thickness of the shift fork ears [A], and mea-

sure the width [B] of the gear grooves.

If the thickness of a shift fork ear is less than the service

limit, the shift fork must be replaced.

Shift Fork Ear Thickness

Standard:

4.9 ∼ 5.0 mm (0.1929 ∼ 0.1969 in.)

Service Limit: 4.8 mm (0.189 in.)

If the gear groove is worn over the service limit, the gear

must be replaced.

Gear Groove Width

Standard:

5.05 ∼ 5.15 mm (0.1988 ∼ 0.2028 in.)

Service Limit:

5.3 mm (0.209 in.)

Shift Fork Guide Pin/Drum Groove Wear

Inspection

• Measure the diameter of each shift fork guide pin [A], and

measure the width [B] of each shift drum groove.

If the guide pin on any shift fork is less than the service

limit, the fork must be replaced.

Shift Fork Guide Pin Diameter

Standard:

5.9 ∼ 6.0 mm (0.2323 ∼ 0.2362 in.)

Service Limit: 5.8 mm (0.228 in.)

If any shift drum groove is worn over the service limit, the

drum must be replaced.

Shift Drum Groove Width

Standard:

6.05 ∼ 6.20 mm (0.2382 ∼ 0.2441 in.)

Service Limit:

6.3 mm (0.248 in.)

9-32 CRANKSHAFT/TRANSMISSION

Transmission

Gear Dog and Gear Dog Hole Damage Inspection

• Visually inspect the gear dogs [A] and gear dog holes [B].

Replace any damaged gears or gears with excessively

worn dogs or dog holes.

Ball and Needle Bearing Wear Inspection

• Check the following ball bearings: right hand drive shaft,

left hand output shaft, and right hand shift drum.

○Since the ball bearings are made to extremely close toler-

ances, the wear must be judged by feel rather than mea-

surement. Clean each bearing in a high flash-point sol-

vent, dry it (do not spin the bearing while it is dry), and oil

it with engine oil.

○Spin [A] the bearing by hand to check its condition.

If the bearing is noisy, does not spin smoothly, or has any

rough spots, replace it.

• Check the following needle bearing: left hand drive shaft,

and right hand output shaft.

○The rollers in a needle bearing normally wear very little,

and wear is difficult to measure. Instead of measuring,

inspect the bearing for abrasion, color change, or other

damage.

If there is any doubt as to the condition of a needle bear-

ing, replace it.

WHEELS/TIRES 10-1

Wheels/Tires

Table of Contents

Exploded View

10-2

Specifications

10-4

Special Tools

10-5

Wheels (Rims)

10-6

Front Wheel Removal

10-6

Front Wheel Installation

10-6

Rear Wheel Removal

10-7

Rear Wheel Installation

10-7

Wheel Inspection

10-9

Axle Inspection

10-9

Balance Inspection

10-10

Balance Adjustment

10-10

Balance Weight Removal

10-10

Balance Weight Installation

10-10

Tires

10-12

Air Pressure Inspection/Adjustment

10-12

Tire Inspection

10-12

Tire Removal

10-12

Tire Installation

10-13

Tire Repair

10-15

Hub Bearing

10-16

Hub Bearing Removal

10-16

Hub Bearing Installation

10-16

Hub Bearing Inspection

10-17

Hub Bearing Lubrication

10-17

Speedometer Gear Housing

10-18

Speedometer Gear Housing Disassembly

10-18

Speedometer Gear Housing Assembly

10-18

Speedometer Gear Housing Lubrication

10-19

10-4 WHEELS/TIRES

Specifications

Item

Standard

Service Limit

Wheels (Rims)

Rim Runout:

Axial

TIR 0.5 mm (0.02 in.) or less

TIR 1.0 mm (0.04 in.)

Radial

TIR 0.8 mm (0.03 in.) or less

TIR 1.0 mm (0.04 in.)

Axle Runout/100 mm (3.94 in.)

TIR 0.1 mm (0.004 in.) or less

TIR 0.2 mm (0.008 in.)

Wheel Balance

10 g (0.35 oz.) or less

- - -

Balance Weights

10 g (0.35 oz.), 20 g (0.71 oz.), 30 g

- - -

(1.06 oz.)

Rim Size:

Front

17 M/C × MT2.75

- - -

Rear

17 M/C × MT3.50

- - -

Tires

Air Pressure (when Cold):

Front

Up to 170 kg (375 lb) load: 200 kPa

- - -

(2.00 kgf/cm², 28 psi)

Rear

Up to 170 kg (375 lb) load: 225 kPa

- - -

(2.25 kgf/cm², 32 psi)

Tread Depth:

Front:

BRIDGESTONE

4.6 mm (0.181 in.)

1 mm (0.04 in.)

DUNLOP

4.5 mm (0.177 in.)

IRC

4.2 mm (0.165 in.)

Rear:

BRIDGESTONE

7.0 mm (0.276 in.)

Up to 130 km/h (80 mph):

2 mm (0.08 in.)

DUNLOP

7.4 mm (0.291 in.)

Over 130 km/h (80 mph):

3 mm (0.12 in.)

IRC

6.5 mm (0.255 in.)

Standard Tires:

Make, Type

Size

Front

BRIDGESTONE BATTLAX BT45F

110/70 17 M/C (54 H)

DUNLOP GT 501FG T/L

IRC RX-01F

110/70 17 M/C (54 S)

Rear

BRIDGESTONE BATTLAX BT45R

130/70 17 M/C (62 H)

DUNLOP GT501 T/L

IRC RX-01R

130/70 17 M/C (62 S)

WARNING

Some replacement tires may adversely affect handling and cause an accident resulting in

serious injury or death. To ensure proper handling and stability, use only the recommended

standard tires for replacement, inflated to the standard pressure.

Kawasaki Ninja 250R Motorcycle. Service Manual (2008-2012 year) - page 2