Snowmobile Yamaha Phazer PZ50W, PZ50GTW, PZ50FXW, PZ50MW, PZ50VTW, PZ50MPW. Manual - part 48

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ENG

CYLINDER HEAD

REMOVAL

1. Remove:

• Cylinder head bolts

NOTE:

Loosen each bolt 1/2 of a turn at a time. After all of
the bolt are fully loosened, remove them. 

5

6

2

3

1

4

INSPECTION

1. Eliminate:

• Combustion chamber carbon deposits 

(with a rounded scraper)

NOTE:

Do not use a sharp instrument to avoid damaging
or scratching: 
• spark plug bore threads 
• valve seats 

2. Inspect:

• Timing chain guide (exhaust side)

Damage/wear 

→ Replace the timing chain

guide.

3. Inspect:

• Cylinder head 

Damage/scratches 

→ Replace. 

• Cylinder head water jacket 

Mineral deposits/rust 

→ Eliminate.

4. Measure:

• Cylinder head warpage 

Out of specification 

→ Resurface the cylinder

head.

Measurement steps:

• Place a straightedge 1 and a thickness gauge

2 across the cylinder head.

• Measure the warpage.
• If the limit is exceeded, resurface the cylinder

head as follows.

• Place a 400 ~ 600 grit wet sandpaper on the

surface plate and resurface the cylinder head
using a figure-eight sanding pattern.

NOTE:

To ensure an even surface, rotate the cylinder head
several times. 

Maximum cylinder head warpage:

0.10 mm (0.0039 in)

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CYLINDER HEAD

INSTALLATION

1. Install:

• Dowel pins 1 
• Gasket 2

 

1

1

2

New

New

2. Install:

• Cylinder head

NOTE:

Pass the timing chain through the timing chain cav-
ity. 

3. Tighten:

• Cylinder head bolts (M10)

NOTE:

The tightening procedure of the cylinder head bolts
is angle controlled, therefore tighten the bolts using
the following procedure.

Tightening steps:

• Lubricate the cylinder head bolts and washers

with engine oil.

• Install the washers and cylinder head bolts.
• Tighten the cylinder head bolts in the proper

tightening sequence as shown.

• Loosen and retighten the cylinder head bolts in

the proper tightening sequence as shown.

T

 

R

.

.

Cylinder head bolt (M10):

1st:

25 Nm (2.5 m · kg, 18 ft · lb) 

T

 

R

.

.

Cylinder head bolt (M10):

2nd:

25 Nm (2.5 m · kg, 18 ft · lb) 

1

2

3

4

5

6

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CYLINDER HEAD

• Tighten the cylinder head bolts further to reach

the specified angle 180° in the proper tightening
sequence as shown.

WARNING

When the bolts are tightened more than the
specified angle, do not loosen the bolt and then
retighten it.
Replace the bolt with a new one and perform
the procedure again.

CAUTION:

• Do not use a torque wrench to tighten the bolt

to the specified angle.

• Tighten the bolt until it is at the specified

angle.

NOTE:

When using a hexagonal bolt, note that the angle
from one corner to another is 60°.

T

 

R

.

.

Cylinder head bolt (M10):

Final:

Specified angle 175 ~ 185°

4. Tighten:

• Cylinder head bolts (M6) 1 

T

 

R

.

.

Cylinder head bolt:

12 Nm (1.2 m · kg, 8.7 ft · lb)

1

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ENG

VALVES AND VALVE SPRINGS

VALVES AND VALVE SPRINGS

Order

Job name/Part name

Q’ty

Remarks

Valves and valve springs removal

Remove the parts in the order listed below.

Cylinder head

Refer to “CYLINDER HEAD”.

1

Valve lifter

10

2

Valve pad

10

3

Valve cotter

20

4

Upper spring seat

10

5

Valve spring

10

6

Exhaust valve

4

7

Intake valve

6

8

Oil seal

10

9

Lower spring seat

10

10

Valve guide

10

For installation, reverse the removal proce-
dure.

M

M

M

M

M

M

New

8

5

4

3

2

1

3

9

New

10

6

10

7

9

8

5

4

3

2

3

1