APRILIA SHIVER 900 Service Station Manual page 255

SHIVER 900
PISTON RINGS
•
Clean off any carbon deposits from the
grooves in the piston rings and from the
rings themselves.
•
Measure the piston ring side clearance
and replace the piston and the piston
rings all together if not complying with
specifications.
Piston ring side clearance:
Top ring (1st slot): 0.030 - 0.065 mm (0.0012 -
0.0026 in)
Intermediate ring (2nd slot): 0.020 - 0.055 mm
(0.0008 - 0.0022 in)
Oil scraper ring (3rd slot): 0.010 - 0.045 mm
(0.0004 - 0.0018 in)
•
Fit the piston ring to the cylinder.
•
Level the installed piston ring with the
piston crown.
•
Measure piston ring port and replace it
if not complying with specifications.
CAUTION
IT IS NOT POSSIBLE TO MEASURE THE CLEARANCE OF
THE END OF THE OIL SCRAPER RING: IF THERE IS EX-
CESSIVE PLAY, REPLACE THE THREE ELASTIC RINGS.
Piston ring end gap:
Top ring: 0.15 - 0.35 mm (0.0059 - 0.0138 in)
The second ring: 0.20 - 0.40 mm (0.0079 -
0.0157 in)
Oil scraper ring: 0.20 - 0.70 mm (0.0079 - 0.0276
in)
PISTON PIN
•
Clean off combustion residues from the piston crown and from the area above the top ring.
•
Check for cracks on the piston and for compression on the piston sliding surface (seizing);
Replace the piston if required.
CAUTION
SMALL STRIATIONS ON THE PISTON LINER ARE ADMISSIBLE.
Engine
ENG - 255