Tappet Clearance - BOMBARDIER Johnson 90 Service Manual

PERIODIC MAINTENANCE
MAINTENANCE ANO TUNE-UP PROCEDURES
Tappet Clearance
lnspect initially after 1 O hours (1 month) and every 200
hours (12 months).
The tappet clearance specification is the same for both
intake and exhaust valves.
Too small a tappet clearance may reduce engine power, too
large a tappet clearance increases valve noise and hastens
valve and seat wear.
When the tappets are set to the specified clearance, the
engine will run without excessive noise from the valve meen­
anism and will deliver full power. In this engine, the tappet
clearance is increased or decreased by replacing the shim
disc, made of a special wear resistant material, fitted to the
top of the tappet.
The shim discs are easy to remove and refit.
Tappet clearance adjustment should be checked and
adjusted:
• at time of periodic inspection
• when valve mechanism is serviced
• when camshafts are disturbad by removing them for
inspectíon
CHECKING ANO ADJUSTING TAPPET CLEARANCE
1. Remove following parts:
• Engine side covers (see page 7-2)
• Flywheel cover
• Spark plugs
2. Remove breather hose
CD
and evaporation hose ~ from
cylinder head cover.
3. Remove fuel hose @ and @ from low pressure fuel
pump.
4. Remove fifteen (15) bolts securing cylinder head cover@
to cylinder head and remove cylinder head cover.
15
Loosening order
14
2