Cylinder Compression - BOMBARDIER Johnson 90 Service Manual

PERIODIC MAINTENANCE
CYLINDER COMPRESSION
CYLINDER COMPRESSION
Cylinder compression:
Standard: 1300 -1700 kPa
(13 -17 kg/cm
2
,
185- 242 psi)
Max. difference between any other cylinders:
100kPa (1.0 kg/cm
2 ,
14 psi)
NOTE:
Figures shown are guidelines only, not absolute service lim­
its.
Low compression pressure can indicate one or more of fol­
lowing:
• Excessively worn cylinder wall
• Worn piston or piston rings
• Stuck piston rings
• Poor seating of valves
• Ruptured or otherwise damaged cylinder head gasket
TEST PROCEDURE
1. Start engine and allow to warm up, then shut engine off.
2. Remove STBD / PORT side covers. (See page 7-2)
3. Remove all spark plugs.
4. lnstall compression gauge hose attachment into plug
hole, then connect compression gauge hose to gauge
hose attachment and compression gauge.
• Compression gauge
• 12 mm Thread Adapter
5. Disconnect safety lanyard (switch plate) from emergency
stop switch.
AWARNING
Dísconnect the safety lanyard from the emergency stop
switch prior to cranking the engine. This will prevent any
residual fuel discharged from the cylinders being ignited
by a spark discharge from the spark plug caps.
6. Disconnect remote control throttle cable from throttle
lever.
7. Move and hold throttle lever in full-open position.
8. While cranking engine with starter motor, note maximum
compression pressure reading on gauge for each cylin­
der.
9. Reinstall parts removed earlier. (spark plugs, side covers,
etc.)
Throttle lever
2-24