HYOSUNG WOW 50, Service Manual

Page: 50 / 133

ENGINE 3-22
■ PISTON PIN O.D.
Using a micrometer, measure the piston pin outside
diameter at three positions.
Service limit
9.980 mm (0.393 in)
Piston pin O.D.
Micrometer(0~25mm) : 09900 - 20201
■
PISTON RINGS
Check each ring for the clearance, reading the clear-
ance with a thickness gauge shown in the illustration. If
the clearance is found to exceed the limit, indicated
below, replace it with a new one.
The clearance of each ring is to be measured with the
ring fitted squarely into the cylinder bore and held at the
least worn part near the cylinder bottom, as shown in
the illustration.
Service limit
0.75 mm (0.030 in)
Piston ring clearance
(Assembly condition)
Thickness gauge : 09900 - 20806
As the piston ring wears, its clearance increases reduc-
ing engine power output because of the resultant blow
by through the enlarged clearance. Here lies the impor-
tance of using piston rings with the clearance within the
limit.
Measure the piston ring free clearance to check the
spring tension.
3.2 mm (0.126 in)
3.1 mm (0.122 in)
Piston ring claerance
(Free condition)
1st
2nd
Service limit