POWERHEAD
4-9
3-/ 4-Cylinder
CYLINDER COMPRESSION TEST
1. Operate engine up to normal operating temperature.
2. Stop engine.
3. Disconnect the magneto leads to disable the ignition system.
WARNING
Ignition system must be disabled to prevent
accidental engine startup during compression
test.
4. Remove all spark plugs and install thread-type compression
tester in spark plug hole.
5. Place throttle in fully open position and crank engine with starter
through at least four compression strokes. Take reading for each
cylinder and verify specified pressure is obtained:
* Compression variation among cylinders should not exceed 15
psi [103 kPa / 1.05 kg/cm
2
].
If variation of cylinder compression exceeds 15 psi [103 kPa / 1.05
kg/cm
2
], check for the following:
• Scored cylinder walls.
• Piston damage.
• Head gasket damage.
• Stuck or broken piston rings.
If cylinder compression is low, engine is difficult to start and runs
poorly, check for the following:
• Scored cylinder walls.
• Piston damage.
• Stuck or worn piston rings.
Model
Cylinder Compression*
psi [kPa / kg/cm
2
]
40 / 50 117 [800 / 8.2] ± 13 %
60 / 70 121 [830 / 8.5] ± 13 %
80 / 90 117 [810 / 8.2] ± 13 %
115 / 120 / 140 128 [880 / 9.0] ± 13 %
1
T1162
To Next Page
Loading...
