Norton Commando Workshop Manual

## Engine/Primary Transmission

# C

8 | Fit and secure the centre bolt nut and washer and tighten to 25 Ibs./ft. (3-456 Kg/m).
The remaining items of the engine plates which have been assembled as a reversal of the dismantling procedure should now be tightened to the recommended torque settings. The 3/8 in. diameter engine to frame stud nuts require a torque figure of 25 to 30 lbs./ft. (3.456 to 4.148 Kg/m) and the 5/16 in "uts to 15 Ibs./ft. (2.074 Kg/m).
Prior to fitting the bottom connection for the rocker feed pipe it is most desirable to prime the crankshaft with approximately a teacup full of oil. This is most easily achieved by the use of an oil syringe, short length of flexible pipe, and a spare rocker feed pipe banjo which can be connected at the rear of the timing case. The priming operation is shown in Fig. C40.

### SECTION C33

### REFITTING PISTONS AND CYLINDER

Throughout the fitting of the pistons and cylinder, take care to protect the connecting rods and pistons from damage caused by these parts coming into contact with the crankcase mouth or cylinder base studs. Proceed as follows:
1 | Fit a new cylinder base, gasket and grease the studs lightly.
2 | Fit one circlip to each piston, sharp edge outwards.
3 | Heat the pistons in hot water to ease entry of the wrist pins (gudgeon pins).
4 | Take special note that the pistons are handed and marked "LH" and "RH" respectively and "EX" at forward side. If the marks are illegible the pistons may be recognised by the fact that the inlet valve cutaway is away from the edge of the crown in each case.
5 | Oil the small end eye and wrist pin bosses and push each wrist pin home by hand.
6 | As each piston is fitted, fit the second circlip sharp end outwards.
7 | Turn the engine crankshaft backwards to lower the pistons, then support the pistons as in Fig. C41 on two suitable bars which must not overlap the timing case.
8 | Position the piston rings with the top compression ring gap central at the front of the piston body and the second taper ring gap central at the rear of the piston body.
9 | Position the scraper ring expander to the side of the piston body with the rail gap 1 in. to the left and right of the expander gap to prevent the rail ends spragging in the connecting rod clearance cutaways in the cylinders.
10 | Smear both piston bodies with clean engine oil. Fit piston ring clamps (also shown in Fig. C41) to keep the piston rings closed. Do not overtighten the ring clamps which would tend to prevent the ring clamps sliding as the cylinder is offered.

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