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5-26 ENGINE TOP END
Cylinder Head
Cylinder Compression Measurement
NOTE
○
Use the battery which is fully charged.
•
Warm up the engine thoroughly.
•
Stop the engine.
•
Remove:
Stick Coils (see Stick Coil Removal in the Electrical Sys-
tem chapter)
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:
57001-1601
L-Shape Hose: 57001-1606
Cylinder Compression
Usable Range:
966
∼ 1 478 kPa (9.9 ∼ 15.1 kgf/cm²,
140
∼ 214 psi) at 280 r/min (rpm)
•
Repeat the measurement for the other cylinders.
•
Install the spark plugs.
Torque - Spark Plugs: 13 N·m (1.3 kgf·m, 115 in·lb)
○
The following table should be consulted if the obtainable compression reading is not within the us-
able range.
Problem Diagnosis Remedy (Action)
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).
Remove the carbon deposits
and replace damaged parts if
necessary.
Cylinder compression
is higher than usable
range
Incorrect cylinder head gasket
thickness
Replace the gasket with a standard
part.
Gas leakage around cylinder head
Replace damaged check gasket
and cylinder head warp.
Bad condition of valve seating Repair if necessary.
Incorrect valve clearance Adjust the valve clearance.
Incorrect piston/cylinder clearance Replace the piston and/or cylinder.
Piston seizure Inspect the cylinder and
replace/repair the cylinder and/or
piston as necessary.
Cylinder compression
is lower than usable
range
Bad condition of piston ring and/or
piston ring grooves.
Replace the piston and/or the
piston rings.
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