Piston Ring Inspection - Yamaha YFM400FWA 2000 5GH3-AE1 Service Manual

CYLINDER AND PISTON
3rd step:
Find the piston-to-cylinder clearance with
the following formula.
Piston-to-cylinder clearance =
Cylinder bore "C" –
Piston skirt diameter "P"
Piston-to-cylinder clearance:
0.040 ~ 0.065 mm
(0.0016 ~ 0.0026 in)
<Limit>: 0.15 mm (0.0059 in)
If out of specification, rebore or replace
the cylinder, and replace the piston and
piston rings as a set.
*********************************

PISTON RING INSPECTION

1.Measure:
Ring side clearance
Use a feeler gauge.
Out of specification → Replace the piston
and rings as a set.
NOTE:
Clean carbon from the piston ring grooves
and rings before measuring the side clear-
ance.
Top
ring
2nd
ring
2.Position:
Piston ring
(in cylinder)
NOTE:
Insert a ring into the cylinder and push it
approximately 40 mm (1.6 in) into the cylin-
der. Push the ring with the piston crown so
that the ring will be at a right angle to the
cylinder bore.
a 40 mm (1.6 in)
4 - 29
ENG
Side clearance
Standard
0.03 ~ 0.08 mm
(0.001 ~ 0.003 in)
0.03 ~ 0.07 mm
(0.001 ~ 0.003 in)
Limit
0.13 mm
(0.005 in)
0.13 mm
(0.005 in)