Yamaha RS90RK, Service Manual

Page: 530 / 841

5-56
ENG
CRANKCASE
8. Straighten the lock washer tab.
9. Loosen:
• Balance weight bolts 1
NOTE:
Place a piece of wood
a
between the balancer
2
and crankcase.
10. Remove:
• Balancer weight 1
• Balancer weight 2
• Water pump drive gear
• Balancer shaft
• Balancer driven gear assembly
a
1
2
a
1
2
INSPECTION
1. Inspect:
• Piston wall
• Cylinder wall
Vertical scratches
→
Rebore or replace the
cylinder, and replace the piston and piston
rings as a set.
2. Measure:
• Piston-to-cylinder clearance
Measurement steps:
1st step:
• Measure cylinder bore “C” with the cylinder bore
gauge 1 .
NOTE:
Measure cylinder bore “C” by taking side-to-side
and front-to-back measurements of the cylinder.
Then, find the average of the measurements.
Cylinder bore “C”
79.000 ~ 79.010 mm
(3.1102 ~ 3.1106 in)
Taper limit “T” 0.050 mm (0.0020 in)
Out of round “R” 0.050 mm (0.0020 in)