Snowmobile Yamaha Phazer PZ50W, PZ50GTW, PZ50FXW, PZ50MW, PZ50VTW, PZ50MPW. Manual - part 57

5-65

ENG

CRANKCASE

5. Measure:

• Piston ring end gap

Out of specification 

→ Replace the piston

rings as a set.

NOTE:

The oil ring expander spacer’s end gap cannot be
measured. If the oil ring rail’s gap is excessive,
replace all three piston rings.

6. Inspect:

• Piston pin

Blue discoloration/grooves 

→ Replace the

piston pin and then check the lubrication sys-
tem.

7. Measure:

• Piston pin outside diameter

Out of specification 

→ Replace the piston pin.

Piston ring end gap:

Top ring:

0.15 ~ 0.25 mm (0.006 ~ 0.010 in)

2nd ring:

0.30 ~ 0.45 mm (0.012 ~ 0.018 in)

Oil ring:

0.10 ~ 0.40 mm (0.004 ~ 0.016 in)

Piston pin outside diameter:

16.991 ~ 17.000 mm
(0.6689 ~ 0.6693 in)

8. Measure:

• Piston pin bore inside diameter

Out of specification 

→ Replace the piston.

Piston pin bore inside diameter:

17.002 ~ 17.013 mm
(0.6694 ~ 0.6698 in)

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ENG

CRANKCASE

9. Calculate:

• Piston pin to piston pin bore clearance

Out of specification 

→ Replace the piston pin

and piston as a set.

Piston pin to piston pin bore clearance = 

Piston pin bore size –
Piston pin outside diameter

Piston pin to piston pin bore clear-
ance:

0.002 ~ 0.022 mm
(0.0001 ~ 0.0009 in)
<Limit>: 0.072 mm (0.0028 in)

10. Measure:

• Crankshaft runout

Use the V-blocks and a dial gauge.
Out of specification 

→ Replace the crank-

shaft.

Dial gauge:

90890-03097, YU-03097

Crankshaft runout:

0.03 mm (0.0012 in)

11. Inspect:

• Crankshaft journal surfaces
• Crankshaft pin surfaces
• Bearing surfaces

Scratches/wear 

→ Replace the crankshaft.

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ENG

CRANKCASE

12. Measure:

• Crankshaft-journal-to-crankshaft-journal-

bearing clearance
Out of specification 

→ Replace the crankshaft

journal bearings.

Measurement steps:

CAUTION:

Do not interchange the crankshaft journal bear-
ings. To obtain the correct crankshaft-journal-
to-crankshaft-journal-bearing clearance and
prevent engine damage, the crankshaft journal
bearings must be installed in their original posi-
tions.

• Clean the crankshaft journal bearings, crank-

shaft journals, and bearing portions of the
crankcase.

• Place the upper crankcase upside down on a

bench.

Crankshaft-journal-to-crankshaft-
journal-bearing clearance:

0.020 ~ 0.044 mm
(0.0008 ~ 0.0017 in)

• Install the crankshaft journal upper bearings 1

and the crankshaft into the upper crankcase.

NOTE:

Align the projections 

a of the crankshaft journal

upper bearings with the notches 

b in the crank-

case.

• Put a piece of Plastigauge

®

  2 on each crank-

shaft journal.

NOTE:

Do not put the Plastigauge

®

 over the oil hole in the

crankshaft journal.

2

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CRANKCASE

• Install the crankshaft journal lower bearings 1

into the lower crankcase and assemble the
crankcase halves.

NOTE:

• Align the projections 

a of the crankshaft journal

lower bearings with the notches 

b in the crank-

case.

• Do not move the crankshaft until the clearance

measurement has been completed.

• Tighten the bolts in the order of the embossed

numbers on the crankcase.

È Cylinder head side
É Oil pan side

M9 

× 105 mm bolts: 1 

M6 

× 70 mm bolts: 2 

M6 

× 65 mm bolts: 3 

M6 

× 50 mm bolts: 4 

M6 

× 50 mm bolt: 5 (with LOCTITE

®

)

M6 

× 35 mm bolts: 6 

NOTE:

Lubricate the crankcase bolt threads with engine
oil.

• Remove the lower crankcase and the crank-

shaft journal lower bearings.

• Measure the compressed Plastigauge

®

 width 

c

on each crankshaft journal.
If the clearance is out of specification, select
replacement crankshaft journal bearings.

T

 

R

.

.

Crankcase bolt:

Bolt 1:

1st: 15 Nm (1.5 m · kg, 11 ft · lb)
2nd: 15 Nm (1.5 m · kg, 11 ft · lb)
Final: Specified angle 65 ~ 70°

Bolt 2 ~ 6:

12 Nm (1.2 m · kg, 8.7 ft · lb)

2

2

2

È

5 3

6

6 4

5

5

5

1

1

1

1

1

1

6

6

3

6

4

É

c