Checking The Piston Pin; Installing The Piston And Cylinder - Yamaha 2004 YP400 Service Manual

CYLINDER AND PISTON
EAS00265

CHECKING THE PISTON PIN

1. Check:
• piston pin
Blue discoloration/grooves → Replace the
piston pin and then check the lubrication
system.
2. Measure:
• piston pin outside diameter a
Out of specification → Replace the piston
pin.
Piston pin outside diameter
3. Measure:
• piston pin bore diameter b (in the piston)
Out of specification → Replace the piston.
Piston pin bore diameter
4. 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 diameter b –
Piston pin outside diameter a
Piston-pin-to-piston-pin-bore
clearance
EAS00267

INSTALLING THE PISTON AND CYLINDER

1. Install:
• top ring
• 2nd ring
• lower oil ring rail
• upper oil ring rail
• oil ring expander
5 - 34
ENG
19.991 ~ 20.000 mm
(0.7870 ~ 0.7874 in)
<Limit>: 19.971 mm (0.7863 in)
20.004 ~ 20.015 mm
(0.7876 ~ 0.7880 in)
<Limit>: 20.045 mm (0.7892 in)
0.004 ~ 0.024 mm
(0.0002 ~ 0.0009 in)
<Limit>: 0.074 mm (0.0029 in)