Snowmobile Yamaha FX10X, FX10RTX, FX10RTRX, FX10RTRAX, FX10MTX, FX10MTRX, FX10MTRAX. Manual - part 4

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COOLING SYSTEM

8. Connect:

• Coolant reservoir hose
• Thermostat outlet hose

9. Fill:

• Cooling system

CAUTION:

• Hard water or salt water is harmful to engine

parts. If soft water is not available, use boiled
or distilled water.

• Do not use water containing impurities or oil.

10. Bleed the air from the cooling system.

Recommended coolant:

High quality ethylene glycol anti-
freeze containing corrosion inhibi-
tors

Coolant mixing ratio (coolant:water):

3:2 (60%:40%)

Total amount:

FX10/FX10RT/FX10RTR/FX10RTRA

3.40 L (2.99 Imp qt, 3.59 US qt)

FX10MT/FX10MTR/FX10MTRA

4.70 L (4.14 Imp qt, 4.97 US qt)

11. Inspect:

• Cooling system

Decrease of pressure (leaks) 

→ Repair as

required.

Inspection steps:

• Attach the cooling system tester 1 and adapter

2 to the radiator filler 3.

• Apply 100 kPa (1.0 kg/cm

2

, 14 psi).

• Measure the pressure with the gauge.

Radiator cap tester:

90890-01325

Radiator pressure tester:

YU-24460-01

Radiator cap tester adapter:

90890-01352

Radiator pressure tester adapter:

YU-33984

1

2

3

3

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COOLING SYSTEM

Air bleeding steps:

NOTE:

For models other than FX10MT/FX10MTR/
FX10MTRA, skip steps 1–3.

• Remove the cap 1 on the heat exchanger pipe.
• While slowly adding coolant to the radiator filler,

drain the coolant until no more air bubbles
appear.

• Install the cap 1.
• Add coolant to the full level 

a.

• Install the radiator cap.

Apply and lock the parking brake. Start the
engine and run it at less than the clutch engage-
ment speed until the coolant circulates (approxi-
mately 3 ~ 5 minutes). The heat exchanger will
be warm to the touch (FX10MT/FX10MTR/
FX10MTRA).

È FX10MT/FX10MTR/FX10MTRA

WARNING

To avoid severe injury or death:
• Make sure the snowmobile is securely sup-

ported with a suitable stand.

• Do not exceed the clutch engagement speed.

Drive line damage and excessive V-belt wear
could occur, or the snowmobile could unex-
pectedly move forward if the clutch engages.

• Operate the engine only in a well-ventilated

area.

• Remove the radiator cap and bleed the cooling

system again, as described above.
No air bubbles 

→ OK.

• Check the coolant level in the coolant reservoir

when the engine is cold. If the coolant level is
below the “LOW” mark 

b, add coolant until it

reaches the “FULL” mark 

c.

1

È

c

b

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VALVE CLEARANCE ADJUSTMENT

VALVE CLEARANCE ADJUSTMENT

NOTE:

• Valve clearance adjustment should be made on a

cold engine, at room temperature.

• When the valve clearance is to be measured or

adjusted, the piston must be at the top dead cen-
ter (TDC) on the compression stroke.

1. Drain:

• Engine oil

Refer to “ENGINE OIL REPLACEMENT”.

2. Remove:

• Fuel tank

Refer to “SEAT AND FUEL TANK” in CHAP-
TER 5. 

• Oil tank

Refer to “OIL TANK” in CHAPTER 5.

3. Remove:

• Cylinder head cover

Refer to “CAMSHAFTS” in CHAPTER 5.

• Timing mark accessing screw 1 
• Crankshaft end accessing screw 2 

4. Measure:

• Valve clearance

Out of specification 

→ Adjust.

Checking steps:

• Turn the crankshaft clockwise.
• When piston #3 is at TDC on the compression

stroke, align the TDC mark 

a on the AC mag-

neto rotor with the mark 

b on the AC magneto

cover.

NOTE:

TDC on the compression stroke can be found when
the camshaft lobes are turned away from each
other.

Valve clearance (cold):

Intake valve:

0.15 ~ 0.22 mm 
(0.0059 ~ 0.0087 in)

Exhaust valve:

0.21 ~ 0.25 mm 
(0.0083 ~ 0.0098 in)

2

1

b

a

EX

IN

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VALVE CLEARANCE ADJUSTMENT

• Measure the valve clearance with a thickness

gauge 1.

NOTE:

• If the valve clearance is incorrect, record the

measured reading.

• Measure the valve clearance in the following

sequence.

È Front

For each cylinder, starting with cylinder #3 at TDC,
turn the crankshaft clockwise as specified in the fol-
lowing table.

É Degrees that the crankshaft is turned clockwise
Ê Cylinder
Ë Combustion cycle

Valve clearance measuring sequence

Cylinder #3 

→ #2 → #1

Cylinder #2

120°

Cylinder #1

240°

1

5. Remove:

• Intake camshaft
• Exhaust camshaft

NOTE:

• Refer to “CAMSHAFTS” in CHAPTER 5.
• When removing the timing chain and camshafts,

fasten a wire to the timing chain to retrieve it if it
falls into the crankcase.