BRP BOMBARDIER DS250 2006 Shop Manual page 105

Section 03 ENGINE
Subsection 09 (PISTON AND CYLINDER)
Measure cylinder head warpage with a straight
edge and a feeler gauge.
vmr2006-074-020
CYLINDER WARPAGE
Service limit
Replace cylinder if out of specifications.
Piston Ring
Using a feeler gauge, measure top and second
rings clearance with piston groove.
vmr2006-074-014
PISTON/RING CLEARANCE
Nominal (new)
Service limit
If out of specifications, replace piston and rings.
Slide rings into cylinder one at a time for measure-
ment. Position ring at 20 mm (.787 in) from top of
cylinder.
NOTE: In order to correctly position ring in cylin-
der, use piston as a pusher.
Using a feeler gauge, check ring end gap.
86
0.50 mm (.020 in)
0.015 - 0.050 mm
(.0006 - .020 in)
0.09 mm (.004 in)
vmr2006-074-050_a
A. 20 mm (.787 in) from top
RING END GAP
Top ring
nd
Nominal (new) 2 ring
Oil ring
Top ring
Service limit
nd
2 ring
Oil ring
Replace rings if gap is out of specifications.
Piston
Inspect piston for scoring, cracking or other dam-
ages. Replace piston as necessary.
Using a micrometer, measure piston as shown.
vmr2006-074-009_a
A. 10 mm (.394 in) perpendicularly (90°) to piston pin
0.15 - 0.30 mm
(.006 - .012 in)
0.30 - 0.45 mm
(.006 - .018 in)
0.20 - 0.70 mm
(.008 - .028 in)
0.50 mm
(.020 in)
0.65 mm
(.026 in)
—
vmr2006-074