5-26 ENGINE TOP END
Cylinder Compression Measurement
Use the battery which is fully charged.
Warm up the engine thoroughly.
Stop the engine.
Spark Plugs (see Spark Plug Replacement in the Peri-
odic Maintenance chapter)
Attach the compression gauge [A] and adapter [B] firmly
into the spark plug hole.
Using the starter motor, turn the engine over with the throt-
tle fully open until the compression gauge stops rising; the
compression is the highest reading obtainable.
Special Tools - Compression Gauge, 20 kgf/cm²: 57001-221
Compression Gauge Adapter, M10 × 1.0:
L-Shape Hose: 57001-1606
Repeat the measurement for the other cylinders.
Install the spark plugs (see Spark Plug Replacement in
the Periodic Maintenance chapter).
The following table should be consulted if the obtainable compression reading is not within the us-
is higher than usable
is lower than usable
770 ∼ 1 198 kPa (7.9 ∼ 12.2 kgf/cm²,
112 ∼ 174 psi) @236 r/min (rpm)
Carbon accumulation on piston and in
combustion chamber possibly due to
damaged valve stem oil seal and/or
damaged piston oil rings (This may be
indicated by white exhaust smoke).
Incorrect cylinder head gasket
Gas leakage around cylinder head
Bad condition of valve seating
Incorrect valve clearance
Incorrect piston/cylinder clearance
Bad condition of piston ring and/or
piston ring grooves
Remove the carbon deposits
and replace damaged parts if
Replace the gasket with a standard
Replace damaged gasket and
check cylinder head warp.
Repair if necessary.
Adjust the valve clearance.
Replace the piston and/or cylinder.
Inspect the cylinder and
replace/repair the cylinder and/or
piston as necessary.
Replace the piston and/or the