Fit a new piston snap ring into the side of the piston so that the ring
opening [A] does not coincide with the slit [B] of the piston pin hole.
When installing a piston pin snap ring, compress it only enough to
install it no more.
Do not reuse snap rings, as removal weakens and deforms
them. They could fall out and score the cylinder wall.
Cylinder Inside Diameter Measurement
Since there is a difference in cylinder wear in different directions,
take a side to side and a front to back measurement at each of the 3
locations (total of 6 measurements) shown in the ﬁgure.
If any of the cylinder inside diameter measurements exceeds the
service limit, the cylinder will have to bored to oversize and then
Cylinder Inside Diameter
ence between any two measurements
53.10 mm or 0.05 mm diffeence between any two
10 mm [A]
60 mm [B]
20 mm [C]
Piston Outside Diameter Measurement
Measure the outside diameter [A] of the piston 7.8 mm [B] up from
the bottom of the piston at a right angle to the direction of the piston
Piston Outside Diameter
Abnormal wear such as a marked diagonal pattern across the
piston skirt may mean a bent connecting rod or crankshaft.
The most accurate way to ﬁnd the piston clearance is by making sep-
arate piston and cylinder diameter measurements and then computing
the difference between the two values. Measure the piston diameter as
just described, and measure the cylinder diameter at the very bottom
of the cylinder.
Whenever the piston or cylinder has been replaced with a new one,
the motorcycle must be broken in the same as with a new machine.
53.009 mm and less than 0.01 mm differ-
ENGINE TOP END 4-29