Valve Clearance Measurement
Note: Valve clearance measurement must be carried out with the engine cold.
1. Remove the camshaft cover (see page 3-6).
2. Remove the spark plugs to reduce compression resistance when turning the engine.
3. Select a high gear and, using the rear wheel, turn the engine until a pair of camshaft lobes are positioned pointing away from the valves.
4. Using feeler gauges, measure and record the clearances for this pair of valves only.
5. Repeat the process until the valve clearances for all valves have been checked.
Note: If the measurement does not fall within the specified range, adjustment must be made. The correct valve clearances are in the range given below:
- Inlet: 0.10 - 0.20 mm
- Exhaust: 0.325 - 0.375 mm
Caution: If the valve clearances are not checked and corrected, wear could cause the valves to remain partly open, which lowers performance, burns the valves and valve seats and may cause serious engine damage.
6. Record the measured valve clearances on a chart similar to the example shown.
Typical Valve Clearance Chart
Inlet Valve No. | Gap Measured |
1 | as measured (mm) |
2 | as measured (mm) |
3 | as measured (mm) |
4 | as measured (mm) |
5 | as measured (mm) |
6 | as measured (mm) |
Exhaust Valve No. | Gap Measured |
1 | as measured (mm) |
2 | as measured (mm) |
3 | as measured (mm) |
4 | as measured (mm) |
5 | as measured (mm) |
6 | as measured (mm) |
Valve Clearance Adjustment
To adjust the valve clearances the camshafts must be removed. Follow the camshaft removal procedure.
1. Remove the camshafts (see page 3-13).
2. Remove the tappet bucket from the cylinder head.
3. Remove the shim from the valve head.
1. Tappet bucket; 2. Shim
Note: The shim may withdraw with the tappet bucket.
4. Measure the original shim, using a micrometer and select the appropriate new shim as required.
Clearance too small:
- Fit a thinner shim.
Clearance too large:
- Fit a thicker shim.
Note: Shims are available ranging from 1.70 mm to 3.00 mm in increments of 0.025 mm.
5. Fit the new shim to the valve head.
6. Lubricate the tappet bucket(s) with a 50/50 solution of engine oil and molybdenum disulphide grease.
7. Refit the tappet bucket.
8. Refit the camshafts (see page 3-15).
9. Re-check all valve clearances.
10. Repeat the procedure if the valves require further adjustment.