Norton Commando Workshop Manual

## Engine/Primary Transmission

# C

### SECTION C10

### ROCKER CLEARANCES

It is essential for the correct valve to rocker clearances, to be maintained to prevent excessively noisy operation and subsequent wear or conversely to prevent insufficient clearances, a loss of compression and burning of the valves and seats. After checking clearances at the time of the first free service, the clearances shouid be checked and corrected as necessary at 5000 mile (8000 Km) intervals. To provide sufficient room at the rocker boxes for satisfactory checking, the fuel tank shouid be removed as in Section F9.
The correct rocker clearances are as below, checked with the engine cold:

Std Commando Engine Combat Engine | Inlet Exhaust Inlet Exhaust | 0.006 in. (0.15 mm) 0.008 in. (0.2 mm) 0.008 in. (0.2 mm) 0.010 in. (0.25 mm)

Proceed to check rocker clearances as below:
1 | Remove the two exhaust and one inlet rocker covers.
2 | To facilitate rotating the engine, remove both sparking plugs.
3 | Rotate the engine, either by the kickstart or by turning the rear wheel forwards with fourth gear engaged, until the left side inlet valve is fully open.
4 | Using the correct feeler gauge (see table above for thickness) check the rocker clearance of the right side inlet valve. Fig. C9 shows the point where the feeler gauge is inserted.
5 | If the clearance is correct i.e. the feeler gauge just nips, proceed to check the next valve as in (7). If gauge will not enter or if it does not nip, adjust as in (6).
6 | Referring to Fig. C9, slacken the adjuster locknut (A) and screw out the adjuster (B) two turns. Place the feeler gauge between the adjuster and end of the valve stem and screw the adjuster in until it just nips the feeler gauge. Tighten the locknut and withdraw the gauge which shouid not be gripped tightly but shouid slide relatively easily from the gap. This clearance is now correct.

7 | Rotate the engine until the right side inlet valve is fully open and adjust the left side inlet valve in a similar manner.
8 | Adjust the right side and left side exhaust valves | in the same sequence but using a feeler gauge in accordance with the table of clearances.

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