Checking, Disassembling And Servicing; Checking And Adjusting; Engine Body - wsm wg972-e4 Workshop Manual

WG972-E4, WSM

4. CHECKING, DISASSEMBLING AND SERVICING

[1] CHECKING AND ADJUSTING

(1) Engine Body

Compression Pressure
1. Operate the engine until it is warmed up.
2. Stop the engine.
3. Remove the air cleaner, the muffler/converter and all spark
plugs.
4. Set a compression tester with the adaptor to the spark plug
hole.
5. Operate the engine with the starter for 5 to 10 seconds keeping
throttle valve fully open and read the maximum compression
pressure.
6. Repeat steps 4 and 5 for each cylinder.
7. If the measurement is below the allowable limit, apply a small
amount of oil to the cylinder wall through the spark plug hole and
measure the compression pressure again.
8. If the compression pressure is still less than the allowable limit,
check the top clearance, valve clearance and cylinder head.
9. If the compression pressure increases after applying oil, check
the cylinder wall and piston rings.
NOTE
• Check the compression pressure with the specified valve
clearance.
• Always use a fully charged battery for performing this test.
• Variances in cylinder compression values should be under
10 %.
• Replace the muffler/converter gasket with a new one.
Factory specification
Compression pressure
Allowable limit
1-S14
ENGINE
1.27 MPa
2
13.0 kgf/cm
185 psi
0.88 MPa
2
9.0 kgf/cm
130 psi
9Y1211108ENS0007US0
KiSC issued 07, 2015 A