2-16 PERIODIC MAINTENANCE
CYLINDER COMPRESSION
NOTE:
Figures shown are guidelines only, not absolute service limits.
Cylinder compression:
960 – 1 400 kPa (9.6 – 14.0 kg/cm
2
, 137 – 199 psi)
Low compression pressure can indicate one or more of the 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 and warm up the engine, then shut the engine off.
2. Remove the spark plug.
3. Install the compression gauge into the plug hole.
09915-64512: Compression gauge
09915-63311: Compression gauge adaptor
4. Disconnect the safety lanyard from the emergency stop
switch.
5. Move and hold the throttle control grip in the full-open posi-
tion.
6. While cranking the engine with the recoil starter, note the
maximum compression pressure reading on the gauge.
Disconnect the safety lanyard from the emergency
stop switch prior to cranking the engine.
This will prevent any residual fuel discharged from the
cylinder from being ignited by a spark discharged
from the spark plug cap.
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