Yamaha YW50AP Service Manual page 77

CYLINDER HEAD, CYLINDER AND PISTON
Cylinder bore
"C"
Taper "T"
Out of round
"R"
C = Maximum D
T=( Maximum D1 or D2 ) - ( Maximum D5 or
D6 )
R=( Maximum D1 D3 or D5 ) - ( Maximum D2
D4 or D6 )
8 If out of specification, rebore or replace cyl-
inder, and replace piston and piston rings
as a set.
2nd step:
8 Measure the piston skirt diameter "p" with
a micrometer.
a 10 mm from the piston bottom edge.
Piston size P
39.958~39.972 mm(1.5731~1.5737 in)
a
8 If out of specification, replace piston and pis-
ton rings as a set.
3rd step:
8 Calculate the piston-to cylinder clearance
with following formula:
Piston-to cylinder clearance = Cylinder bore
" C "- Piston skirt diameter "p"
8 If out of specification, rebore or replace cyl-
inder, and replace piston and piston rings as
a set.
Piston-to cylinder clearance:
0.035 ~ 0.040mm (0.014 ~ 0.0016 in)
Limit : 0.10 mm (0.0039 in)
4-6
ENG
Standard Wear limit
40.10 mm
40.000~40.014mm
(1.5748~1.5754 in) (1.5787 in)
0.05 mm
–
(0.0020 in)
– 0.03 mm
(0.0012 in)