BOMBARDIER 1982 Shop Manual page 160

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SECTION 02 ENGINE
SUB-SECTION 07 (640 ENGINE TYPE)
CLEANING
Discard all gaskets.
Clean all metal components in a non-ferrous metal clean-
er.
Scrape off carbon formation from cylinder exhaust port,
cylinder head and piston dome using a wooden spatula .
O
NOTE: The letters "AUS" (over an arrow on the
piston dome) must be visible after cleaning.
Clean the piston ring grooves with a groove cleaner
tool, or with a piece of broken ring.
DISASSEMBL Y
@
@
® Place a clean cloth over crankcase to prevent
circlips from falling into crankcase. Use a pointed tool to
remove circlips from piston.
_ CAUTION: When tapping out gudgeon pins, hold
" . piston firmly in place to eliminate the possibilities
of transmitting shock and pressure to the connecting
rod.
INSPECTION
The inspection of the engine top end must include the
following measurements:
TOLERANCES
MEASUREMENTS FITTING NEW PARTS WEAR LIMIT
(MIN.) (MAX .)
Cylinder taper
NA NA
.08 mm
10031"1
Cylinder out of
NA NA
.05 mm
round
1.0019")
Cylinder / piston .08 mm .10 mm .22 mm
clearance 10031") 1.0039") 10086")
Ring/piston groove .04 mm
.11 mm 1.0
mm
clearance 1.0016") 10043") 1.0394")
Ring end gap
.25 mm .40 mm 1.2 mm
1.0098") 1.0157" ) 1.0472")
O NOTE: For the measurement procedures, refer to
"Engin e Tolerances Measurement", section 02,
sub-section 09.
PAGE 158
ASSEMBLY
@At assembly, place the pistons over the connecting
rods with the letters" AU S" (over an arrow on the pis-
ton dome) facing in the direction of the exhaust port.
EXHAUST
Also make sure that the piston windows are aligned
with the crankcase transfer passages when the
gudgeon pin orifice is in-line with the connecting rod
bore.
®To minimize the effect of acceleration forces on cir-
clip, install each circlip so the circlip break is at 6 o'clock
as illustrated.