ENGINE TOP END 5-25

Cylinder Head

Cylinder Compression Measurement

NOTE

○Use the battery which is fully charged.

•Warm up the engine thoroughly.

•Stop the engine.

•Remove the spark plugs (see Spark Plug Replacement in the Periodic 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 throttle 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: 980 1 498 kPa (10.0 15.3 kgf/cm², 142 217 psi) at 240 r/min (rpm)

•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 usable range.

	Problem	Diagnosis	Remedy (Action)
	Cylinder	Carbon accumulation on piston and in	Remove the carbon deposits and
	compression	combustion chamber possibly due to	replace damaged parts if necessary.
	is higher than	damaged valve stem oil seal and/or
	usable range	damaged piston oil rings (This may be
		indicated by white exhaust smoke).
		Incorrect cylinder head gasket thickness	Replace the gasket with a standard part.
	Cylinder	Gas leakage around cylinder head	Replace damaged check gasket and
	compression		cylinder head warp.
	is lower than
		Bad condition of valve seating	Repair if necessary.
	usable range
		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.
		Bad condition of piston ring and/or piston	Replace the piston and/or the piston
		ring grooves	rings.

5-26 ENGINE TOP END

Cylinder Head

Cylinder Head Removal

•Drain:

Coolant (see Coolant Change in the Periodic Maintenance chapter)

Engine Oil (see Engine Oil Change in the Periodic Maintenance chapter)

•Remove:

Engine (see Engine Removal in the Engine Removal/Installation chapter)

Cylinder Head Cover (see Cylinder Head Cover Removal)

Camshafts (see Camshaft Removal)

•Remove the front camshaft chain guide bolt (upper) [A].

•Remove:

Front Camshaft Chain Guide Bolt (Lower) [A] Collar

Front Camshaft Chain Guide [B]

•Loosen the M6 and M9 cylinder head bolts as shown sequence [1 12] in the figure, and remove them with washers.

•Remove the cylinder head.

ENGINE TOP END 5-27

Cylinder Head

Cylinder Head Installation

NOTE

○The camshaft cap is machined with the cylinder head, so if a new cylinder head is installed, use the cap that is supplied with the new head.

•Install the dowel pins.

•Replace the cylinder head gasket with a new one.

•Replace the cylinder head bolt washers with new ones.

•Apply molybdenum disulfide oil solution to both sides [A] of the cylinder head bolt washers and the threads [B] of the head bolts [C].

•Tighten the M9 cylinder head bolts as shown sequence [110] in the figure.

Torque - Cylinder Head Bolts (M9):

First: 15 N·m (1.5 kgf·m, 11 ft·lb) Final: 39 N·m (4.0 kgf·m, 29 ft·lb)

•Tighten the M6 cylinder head bolts as shown sequence [11, 12] in the figure.

Torque - Cylinder Head Bolts (M6): 12 N·m (1.2 kgf·m, 106 in·lb)

•Install:

Front Camshaft Chain Guide [A] New O-ring [B]

Collar [C]

○Apply grease to the new O-ring.

•Tighten:

Torque - Front Camshaft Chain Guide Bolt (Upper) [D]: 25 N·m (2.5 kgf·m, 18 ft·lb)

Front Camshaft Chain Guide Bolt (Lower) [E]: 12 N·m (1.2 kgf·m, 106 in·lb)

•Install the removed parts (see appropriate chapters).

5-28 ENGINE TOP END

Cylinder Head

Cylinder Head Warp Inspection

•Clean the cylinder head.

•Lay a straightedge across the lower surface of the cylinder head at several positions.

•Use a thickness gauge [A] to measure the space between the straightedge [B] and the head.

Cylinder Head Warp

Standard:

– – –

Service Limit: 0.05 mm (0.002 in.)

If the cylinder head is warped more than the service limit, replace it.

If the cylinder head is warped less than the service limit, repair the head by rubbing the lower surface on emery paper secured to a surface plate (first No. 200, then No. 400).