Yamaha MA190, Service Manual

Page: 59 / 66

54
TIP
This clearance must be checked before and
after repairing.
d. Piston ring side clearance
9
Check with placing each ring into each-
self groove.
9
The piston ring should be freely turned
without loosening and sticking.
9
Then measure with inserting feeler into
clearance of the ring and upper and
lower face.
Standard (The first
ring/second ring)
Service limit
0.04–0.08/
0.04–0.08 mm
0.150 mm
e. Piston ring end gap
Flatly place the piston into the cylinder
with pushing the piston head to working
position. Measure the opening clearance
with feeler, that clearance not too big or
not to small, too big can result in cylinder
sealing performance poor while too small
can result in piston expanded from heat-
ing and blocked in the cylinder, thus
causing piston broken and “sticking”. If
opening clearance is too small, file the
opening with fine flat file. Often check in
the cylinder when filing until the proper
clearance is got.
Standard Service limit
The first ring
0.13–0.28
mm
1.0 mm
The second
ring
0.20–0.40
mm
1.0 mm
4-3 Engine
Feeler
Piston ring