Checking The Cylinder And Piston - Yamaha PW50W 2007 Service Manual

CYLINDER HEAD, CYLINDER AND PISTON
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a. Place a straightedge 1 and a thickness
gauge 2 across the cylinder head.
b. Measure the warpage.
c. If the limit is exceeded, resurface the
cylinder head as follows.
d. Place a 400-600 grit wet sandpaper on
the surface plate and resurface the cylin-
der head using a figure-eight sanding pat-
tern.
NOTE:
To ensure an even surface, rotate the cylinder
head several times.
e. After resurfacing, out of specification →
Replace the cylinder head.
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CHECKING THE CYLINDER AND PISTON

1. Check:
9 Piston wall
9 Cylinder wall
Vertical scratches → Rebore or replace
the cylinder, and replace the piston and
piston rings as a set.
2. Measure:
9 Piston-to-cylinder clearance
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a. Measure cylinder bore "C" with the cylin-
der bore gauge.
NOTE:
Measure cylinder bore "C" by taking side-to-
side and front-to-back measurements of the
cylinder. Then, find the average of the mea-
surements.
Bore "C"
Bore
39.993-40.012 mm (1.5745-1.5753 in)
Taper limit "T"
Warp limit
0.050 mm (0.0020 in)
5-12
ENG