31.11 Measure the cylinder bore in the directions shown with a telescoping gauge

the average cylinder dimension at each point (see illustration). Compare the results to the specifications at the beginning of this Chapter. If the cylinders are worn, oval or tapered beyond the service limit, or badly scratched, scuffed or scored, the cylinder block must be rebored. Oversize pistons are available (see Section 23).

12. If the precision measuring tools are not available, take the upper crankcase to a Honda dealer or motorcycle engineer for assessment and advice.

13. If the cylinders are in good condition and the piston-to-bore clearance is within specifications, the cylinders should be honed (de-glazed). To perform this operation you will need the proper size flexible hone with fine stones, or a bottle-brush type hone, plenty of light oil or honing oil, some clean rags and an electric drill motor.

14. Clamp the block/crankcase securely so that the bores are horizontal rather than vertical. Mount the hone in a drill motor, compress the stones and insert the hone into the cylinder. Thoroughly lubricate the cylinder, then turn on the drill and move the hone up and down in the cylinder at a pace which produces a fine cross-hatch pattern on the cylinder wall with the lines intersecting at an angle of approximately 60°. Be sure to use plenty of lubricant and do not take off any more material than is necessary to produce the desired effect. Do not withdraw the hone from the cylinder while it is still turning. Switch off the drill and continue to move it up and down in the cylinder until it has stopped turning, then compress the stones and withdraw the hone. Wipe the oil from the cylinder and repeat the procedure on the

other cylinder. Remember, do not take too much material from the cylinder wall.

15. Wash the cylinders thoroughly with warm soapy water to remove all traces of the abrasive grit produced during the honing operation. Be sure to run a brush through the oil and coolant passages and flush them with running water. After rinsing, dry the cylinders thoroughly and apply a thin coat of light, rust-preventative oil to all machined surfaces.

16. If you do not have the equipment or desire to perform the honing operation, take the block to a Honda dealer or motorcycle engineer.

32 Initial start-up after overhaul

1. Make sure the engine oil level and coolant level are correct (see Daily (pre-ride) checks). Turn the fuel tap to the OFF position.

2. Pull the plug caps off the spark plugs and insert a spare spark plug into each cap. Position the spare plugs so that their bodies are earthed (grounded) against the engine. Turn on the ignition switch and crank the engine over with the starter until the oil pressure warning light goes off (which indicates that oil pressure exists). Turn off the ignition. Remove the spare spark plugs and reconnect the plug caps.

3. Make sure there is fuel in the tank, then turn the fuel tap to the ON or RES position as required, and set the choke.

4. Start the engine and allow it to run at a moderately fast idle until it reaches operating temperature.

A Warning: If the oil pressure indicator light doesn't go off, or it comes on while the engine is running, stop the engine immediately and refer to Chapter 1, Section 33 for the oil pressure checking procedure.

5. Check carefully that there are no oil or coolant leaks and make sure the transmission and controls, especially the brakes, function properly before road testing the machine. Refer to Section 33 for the recommended running-in procedure.

6. Upon completion of the road test, and after the engine has cooled down completely, recheck the valve clearances (see Chapter 1) and check the engine oil and coolant levels (see Daily (pre-ride) checks).

33 Recommended running-in procedure

1. Treat the machine gently for the first few miles to make sure oil has circulated throughout the engine and any new parts installed have started to seat.

2. Even greater care is necessary if new pistons/rings or new crankshaft or connecting rod bearings have been installed. This means greater use of the transmission and a restraining hand on the throttle until at least 600 miles (1000 km) have been covered. There's no point in keeping to any set road speed - the main idea is to keep from labouring the engine and to gradually increase performance up to the 1000 mile (1600 km) mark. These recommendations can be lessened when only a partial overhaul has been done, although it depends on the nature of the work carried out and which components have been renewed. Experience is the best guide, since it's easy to tell when an engine is running freely. The table below showing maximum engine speed limitations, which Honda provide for new motorcycles, can be used as a guide.

3. If a lubrication failure is suspected, stop the engine immediately and try to find the cause. If an engine is run without oil, even for a short period of time, severe damage will occur.

3-1

^{Chapter 3}

Cooling system

Contents

Coolant hoses - removal and installation 9

Coolant level check see Daily (pre-ride) checks

Coolant reservoir - removal and installation 3

Coolant temperature gauge and sensor - check and

replacement 5

Cooling fan and cooling fan switch - check and replacement 4

Cooling system checks see Chapter 1

Cooling system draining, flushing and refilling see Chapter 1

General information 1

Pressure cap - check 2

Radiator - removal and installation 7

Thermostat and thermostat housing - removal,

check and installation 6

Water pump - check, removal and installation 8

Degrees of difficulty

Easy, suitable for novice with little experience

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Fairly easy, suitable for beginner with some experience

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Fairly difficult, |k

suitable for competent >a^ DIY mechanic ||S

Difficult, suitable for ^ experienced DIY ^ mechanic 2S