Use of Engine Service Platform
13
Inspection and maintenance on CBU
Check of compression pressure
Warning
l The oil temperature is very hot when the engine remains in warm-up state.
In case of disassembly and assembly, be cautious of scald.
1. Warn up the engine to the normal operating temperature;
2. Flame out and let the engine cool down for 10mins;
3. Remove the fuel pump relay (See the appropriate CBU Service Manual);
4. Remove the spark plug of cylinder 1(See the Ignition and Control Systems);
5. Disconnect the harness joint of ignition coil (See the appropriate CBU Service
Manual);
6. Connect a pressure gauge in the spark plug hole of cylinder 1;
7. Step to the end the throttle pedal and start the engine;
8. Record the max.reading of barometer;
9. Check each cylinder pressure as per the above-said method.
l If the pressure of one or more cylinders are too low, or the pressure
difference between the cylinders too much exceeded the specified range,
drop some dots of engine oil inside and recheck the pressure;
— If the pressure increased, the piston, piston ring and cylinder wall may be worn and
the overhaul is necessary;
— If the pressure of adjacent cylinder is too low, it means that the cylinder pad may have
been damaged or the cylinder head deformed, the overhaul is necessary;
— If the compression pressure is still low, it indicates that the valve may be clamped or
the seal surface is not in tight contact and the overhaul is necessary;
— Compression pressure
kPa {kgf/cm
2
, psi}[rpm]
Items Compression pressure
Standard value 1370{14.0, 199}[300]
Minimum limit 1080{11.0, 156}[300]
Maximum limit of pressure difference
among cylinders
200kPa {2.0kgf/cm
2
, 28psi}
10. Take out the pressure gauge.
11. Connect the ignition coil harness.
12. Fit the fuel pump relay.
13. Fit the spark plug.
Tightening torque: 22～25N·m{2.3～2.6kgf·m, 16～18ft·lbf}.
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