Insufficient compression pressure will result in performance loss and may indicate leaking valves or worn or damaged piston rings. Procedure:
1. Make sure the valve clearance is correct.
2. Warm up the engine 2^3 minutes.
3. Remove all the spark plugs.
4. Install a compression check gauge.
1. Remove the alien bolt that holds the timing plate.
2. Remove the pick-up coil securing screws and remove the pick-up coil assembly.
A. Battery
1. The fluid level should be between the upper and lower level marks. Use only distilled water if refilling is necessary.
CAUTION:
Normal tap water contains minerals which are harmful to a battery; therefore, refill only with distilled water.
1. Camshaft
a. The cam lobe metal surface may have a blue discoloration due to excessive friction. The metal surface could also start to flake off or become pitted.
b. If any of the above wear conditions are readily visible, the camshaft should be replaced.
1. Crankshaft run-out
Support the crankshaft at both ends on V-blocks. Measure the amount of crankshaft run-out on the main bearing journals with a dial gauge while rotating crankshaft.
Run-out limit: 0.03 mm (0.0012 in)
If run-out exceeds limit, replace crankshaft.
2. Inspection of bearings
a. Install the new cylinder head gasket. Install the dowel pins and "o-rings".
b. Install the cylinder head onto the cylinder. Pull the cam chain through the cylinder head as it is installed. Tie the cam chain so that it does not fall into the crankcase.
Crankcase disassembly
1. Remove the right-front crankcase cover.
2. Remove the upper crankcase bolts, starting the highest numbered bolt.
Turn over the engine and remove the lower crankcase bolts.
CRANKCASE TIGHTENING SEQUENCE
LOWERCASE
1. Headlight bulb replacement
a. Remove the cowling assembly.
b. Remove the 2 screws holding the light unit assembly to the headlight body.
a. Install the rotor onto the shaft and tighten the bolt using the rotor holding tool (special tool) as shown.
1. Rotor holding tool
Tightening torque: 3.5 m-kg (25.5 ft-lb)
b. Install the stator coil assembly onto the crankcase and align the grooves on the stator core with the bolt holes on the crankcase.
The cam chain becomes stretched with use, resulting in improper valve timing and engine noise. To prevent this, the cam chain ten-sioner must be adjusted regularly.
1. Remove the timing plate cover.
2. Slowly rotate the crankshaft counterclockwise until the "C" mark on the timing plate aligns with the stationary pointer.
