Checking The Piston; Piston Rings - APRILIA SL 750 SHIVER Service Station Manual

SL 750 SHIVER

Checking the piston

•
Measure the piston skirt diameter "P"
with a micrometer (a=10 mm (0.39 in)
from the piston lower border).
•
Calculate the clearance between pis-
ton and cylinder as follows:
Piston - cylinder clearance C = C - P
Piston - cylinder clearance: 0.050 - 0.064 mm
(0.00197 - 0.00252 in) Limit: 0.100 mm (0.00039
in)
•
Replace the cylinder, the piston and
the piston ring all together if not com-
plying with specifications.

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 GAP
OF THE OIL SCRAPER RING END: IF CLEAR-
ANCE IS EXCESSIVE, REPLACE THE THREE
PISTON RINGS.
Engine
ENG - 43