Piston Ring Arrangement

Badly worn cylinder bores produce excessive smoking ; from the exhaUsts, initially iri the form of a blue, haze ; : tending to deveipp into a white haze as the wear becomes more pronounced, The other indication is piston slap, a form of metallic rattle which occurs when there is little load oh thé enginé. If the top qf thé bore iè examined carefullyJf will be found thai there Is a ridge on the thrust side; the depth of which will vary according to the raie of wear which has taken pièce*

11,10 Carefully install the block as described in text

Installation

1 On 600 models, if removed, install the oil jets in the crankcase top surface ensuring that their smaller holes are facing upwards (see illustration).

8 On all models refit the dowels to the crankcase and install a new base gasket (see illustration). Inspect the O-rings which are fitted over the lower end of each liner and renew any which are damaged.

9 Note that it is advisable to enlist the help of an assistant to refit the cylinder block. Lubricate the pistons and surface of the cylinder bores with clean engine oil. Pass the camchain through its tunnel in the block and slide the block into position.

10 The cylinder bores have a generous lead-in for the pistons at the bottom, although on a multi-cylinder engine such as this it would be an advantage to use the special Honda piston ring compressors. In the absence of these it is possible to lead the pistons into the bores gently, working across from one side to the other, guiding in one ring at a time whilst gently tapping on the cylinder block top surface (see illustration).

Caution: Great care must be taken not to put too much pressure on the piston rings as they are easily broken. The above process takes time and patience and must not be rushed. Once all the piston rings have entered the bore push the cylinder block down until it seats firmly on the base gasket.

11 Install the cylinder block retaining bolt, tightening it only finger-tight at this stage. Check that the crankshaft can be smoothly rotated whilst holding the block down and keeping the camchain taut.

12 On 600 models fit the coolant hose to the rear of the block, securing it in position by tightening its hose clamp securely. On 1000 models check the condition of the coolant pipe O-rings, renewing them if necessary, then refit the pipe to the block, tightening its retaining bolts securely.

12 Pistons and rings - removal ± inspection and-installation: ;

Note: The pistons and rings can be removed with the engine in the frame.

Removal

1 Remove the cylinder block as described in Section 11.

2 Remove the circlips from the pistons by inserting a small flat-bladed screwdriver into the groove in the piston boss and levering them out of position. Discard all circlips regardless of their apparent condition and use new ones on installation.

3 Press each piston pin out of position, noting that if the pins are a tight fit in the piston bosses it is advisable to warm the pistons before attempting to remove them. A rag which has been moistened in very hot water should be sufficient to expand the piston bosses when wrapped around the piston - take care to avoid scalding the hands! Do not use excessive force to remove the piston pins; if they are especially tight, make up a drawbolt arrangement to press them out of position. Using a spirit-based marker or scriber, mark each piston inside the skirt so that it can be refitted in its original bore on installation.

4 The piston rings can be removed by holding the piston in both hands and gently prising the ring ends apart until they can be lifted out of their grooves and onto the piston lands, one side at a time. The rings can then be slipped off the piston and put to one side for examination. Store the rings in the exact order that they were fitted as a guide to reassembly. If the rings are stuck in their grooves by excessive carbon deposits use three strips of thin metal to remove them (see illustration). Be careful as the rings are brittle and will break easily if overstressed.

Piston Ring Off Thrust Side
12.4 Method of removing rings stuck in their grooves by deposits

Inspection

5 If the cylinders are to rebored, the existing pistons and rings can de disregarded because they wili be replaced with new items. If, however, the bores have been cleaned and checked as described in the preceding Section and are to be re-used, clean and check the pistons and rings as follows.

6 Remove all traces of carbon from the piston crowns using a blunt-ended scraper to avoid damaging the piston surface. Finish off by polishing the crowns of the pistons with metal polish to prevent carbon adhering so rapidly in future. Note: Never use emery cloth on the soft aluminium alloy of the piston.

7 Piston wear usually occurs at the skirt or lower end of the piston and takes the form of vertical streaks or score marks on the thrust side of the piston. Damage of this nature will necessitate renewal and is checked by measuring the outside diameter of the skirt at a point 10 mm (0.4 in) from the base of the piston and at right angles to the piston pin axis (see illustration). If any piston has worn to or beyond its service limit, it must be renewed.

8 After the engine has covered a high mileage, it is possible that the ring grooves

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12.7 Measuring piston diameter

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12.7 Measuring piston diameter may have become enlarged. Refit the rings to the piston and measure the clearance between the ring and groove using feeler gauges (see illustration). If the gap exceeds the service limit the piston and/or piston rings must be renewed.

9 To measure the piston ring end gap, insert the ring into the lower end of its bore, using the crown of the bare piston to locate it. Ensure that it is square in the bore and measure the end gap of the ring using feeler gauges {see illustration). If the ring gap exceeds the limits given, the rings should be renewed as a set.

10 It is also necessary to check the end gap when fitting new rings. If there is insufficient clearance, the rings will break up in the bore whilst the engine is running causing extensive engine damage. If necessary, the end gap can be increased by carefully filing the ends of the rings with a fine file. Support the ring on the end as much as possible to avoid breakage and ensure that the ring ends are kept square. Remove only a small amount at a time and keep rechecking the end gap in the bore.

11 Measure the outside diameter of the piston pin at several points along its bearing surface and renew it if it has worn beyond the service limit. If possible, also measure the internal diameter of the piston pin bore in the piston and the connecting rod small-end bore; compare these with the limits given in the Specifications, renewing components as necessary.

12.9 Checking piston ring end gap

12.8 Checking piston ring groove clearance

12.9 Checking piston ring end gap

Arrangement Rings Piston

12.12 Piston ring end gap arrangement

1 Top ring 4 Oil expander ring complete

2 Top ring marking (N or R) 5 Expander ring

3 Second ring 6 Side rails

12.12 Piston ring end gap arrangement

1 Top ring 4 Oil expander ring complete

2 Top ring marking (N or R) 5 Expander ring

3 Second ring 6 Side rails installation

12 Refit the rings to the piston using the method employed on removal and position them as follows. The oil expander ring is fitted first followed by its side rails. Position the side rails so that thinner end gaps are at least 20 mm (0.8 in) each side of the oil expander ring end gap (see illustration).

13 The second compression ring is easily identified by its tapered outer edge and must be fitted so that the widest point of the ring is at the bottom. The ring end gap should be positioned approximately 120° from that of the oil expander ring. The top ring is marked on one surface with either an N or R and must be installed with this mark on the upper surface of the ring and the ring end gap positioned approximately 120° from the end gaps of both the second and oil expander ring (see illustration). Ensure that all rings can move freely in their grooves.

14 Check that each piston has one new circiip fitted to it and insert the piston pin from the opposite side, if it is a tight fit, the piston should be warmed first. If the original pistons are being refitted, use the marks made on disassembly to ensure each piston is refitted to its correct bore.

15 Lubricate the piston pin and connecting rod bores with clean engine oil and lower each piston in turn over its respective connecting rod ensuring that the IN mark on the crown of the piston is on the inlet valve side. Push the piston pin through both piston bosses and the connecting rod small-end (see illustration). If

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12.15a Ensure piston is correctly positioned and insert the piston pin

12,15b Secure the piston pin in place using a new circiip

12.13 Top piston ring can be identified by mark on its upper surface necessary the pins can be tapped carefully into position, using a hammer and suitable drift, whilst supporting the connecting rod and piston. Secure each piston pin in position with a second new circiip, ensuring that it is correctly , seated in its groove (see illustration).

Note: The clutch can be removed with the engine in the frame.

1 If the engine is in the frame, drain the engine oil as described in Chapter 1, and remove the right lower or side fairing section (as appropriate) as described in Chapter 6. On 600 models it will also be necessary to remove the fuel tank as described in Chapter 4 and disconnect the three-pin block connector joining the three yellow alternator wires. Follow the procedure given under the relevant sub-heading (see illustrations).

600 models

2 Slacken and remove all the right crankcase cover retaining bolts and, if the engine is in the frame, disconnect the cable from the clutch lifting arm5 removing it along with its mounting bracket. Carefully lift the cover away from the engine whilst catching any residual oil which may be released as the cover is removed. Note the two locating dowels fitted to the crankcase and remove these for safekeeping if they are loose. Ensure that the clutch pushrod is securely in place in the crankcase cover.

3 Progressively slacken the clutch spring retaining bolts until spring pressure is released then remove the clutch lifting plate and springs.

4 The clutch centre is staked to the shaft for security. Prior to its removal, unstake the nut using a drill, taking great care not to damage the mainshaft (input shaft) threads.

5 in the absence of the Honda service tool, Part Number 07GMB-KT80100, it will be necessary to devise some method of preventing the clutch centre rotating as the

13.1a Clutch - 600 models

8 Clutch centre

9 Spring seat

10 Anti-judder spring

11 Outer friction piate

1 Pushrod

2 Bearing

3 Spring retaining bolt doff

4 Lifting plate

5 Spring-4 off

6 Nut

7 Washer

13.1a Clutch - 600 models

8 Clutch centre

9 Spring seat

10 Anti-judder spring

11 Outer friction piate

12 Plain piate - 5 off

13 Friction plate - 5 off

14 Pressure plate

15 Clutch drum

16 Needle bearing

17 Centre collar

18 Oil pump drive gear

19 Spacer

13.1b Clutch - 1000 models

1 Spring retaining bolt 5 off

3 Pressure plate

4 Bearing

5 Pressure plate lifter

6 Pushrod

7 Nut

8 Washer

13.1b Clutch - 1000 models

9 Friction plate - 8 off 13 Spring seat

10 Plain plate - 8 off

11 Inner friction plate

12 Anti-judder spring

14 Clutch centre

15 Thrust washer (K models onward)

16 Clutch drum

17 Needle bearing

18 Centre collar

19 Thrust washer

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13.5a On 600 models slacken clutch centre nut...

13.5b

whilst retaining the clutch centre as described in text

13-14 On 1000 models hold clutch centre as shown whilst slackening nut

centre nut is slackened. If the engine is in the frame, lock the clutch through the transmission, by selecting top gear and applying the rear brake hard whilst the nut is slackened. If the engine is out of the frame, pass a close-fitting ring spanner over the countershaft (output shaft) splines, select top gear and hold the spanner whilst the nut is slackened (see illustrations).

6 Remove the nut and discard it; a new one must be used on installation. Remove the washer noting which way around it is fitted.

7 Withdraw the clutch centre followed by the outer friction plate. Note: The outer friction plate is different to the others. Mark the plate in some way to ensure that it is refitted in its original position. Remove the spring seat and anti-judder spring, noting which way around the spring is fitted, followed by the remaining plain and friction plates.

8 Remove the clutch pressure plate then withdraw the clutch drum and needle bearing.

9 To remove the oil pump drive assembly, slacken the bolt which secures the driven sprocket to the pump then remove both sprockets and the chain as an assembly. Slide the clutch drum centre collar off the mainshaft followed by the large spacer.

1000 models

10 Slacken and remove all the right crankcase cover retaining bolts, noting the correct positions of the two wiring clamps, and carefully lift the cover and heat protector bar away from the engine. Be prepared to catch any residual oil which will be released as the cover is removed.

11 Progressively slacken the clutch spring retaining bolts, until all spring pressure is released, and remove the clutch springs and their retaining bolts. Remove the pressure plate followed by the pressure plate lifter from the end of the pushrod and withdraw the pushrod itself.

12 Remove the friction and plain plates followed by the anti-judder spring, spring seat, inner plain plate and clutch centre. Note: The inner friction plate is different to all the others. Mark this plate in some way to ensure it is fitted in its original position. Also make a note of which way around the anti-judder spring is fitted to use as a guide on reassembly.

13 The clutch nut is staked to the shaft for security. Prior to its removal, unstake the nut using a drill, taking great care not to damage the mainshaft (output shaft) threads. Note that the nut must be renewed on installation, A six-sided hexagonal nut is used on H and J models, and a bi-hexagonal nut on K models onward.

14 A holding tool will be required to prevent the clutch centre rotating whilst the nut is slackened (see illustration). In the absence of the correct Honda service tool, Part Number 07724-0050001, a simple alternative can be made (see Tool Tip). Alternatively, if the engine is in the frame the centre can be retained as described in paragraph 4. Remove the nut and discard it; a new one must be used on reassembly. Remove the washer and clutch centre followed by the large thrust washer (K models onward).

15 Withdraw the clutch drum centre collar, using two pairs of pointed-nose pliers, and remove the needle roller bearing and clutch drum. Remove the thrust washer from the mainshaft.

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1 After an extended period of service the clutch friction plates will wear and promote clutch slip. Measure the thickness of each friction plate using a vernier caliper. If any plate has worn to or beyond the service limit given in the Specifications, the friction plates must be renewed as a set.

2 The plain plates should not show any signs of excess heating (blueing). Check for warpage using a flat surface and feeler gauges. If any plate exceeds the maximum

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Responses

  • tekle
    How to gab position rings on a 4 groove piston?
    3 years ago
  • jennifer
    How motorcycle piston rings is arranged?
    2 years ago
  • tewolde
    How to replace piston rings cbr 600?
    2 years ago

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