Ransomes Matador 71 Safety And Operation Manual page 20

GB-18
Fig. 15
Monthly
Spark plug
(Fig. 15)
Remove the plug and check condition. Good operating
conditions are indicated if the plug has a light coating of
grey or tan deposit. A white blistered coat could
indicate overheating. A black (carbon) coating may
indicate an over rich fuel mixture caused by a blocked
air cleaner or incorrect carburettor adjustment.
DO NOT sand blast, wire brush or otherwise service a
plug in poor condition.
Best results are obtained with a new plug; set the gap
to 0.75mm (0.030in).
Annually (Every 500 working hours)
Valve Clearance
1. Remove tappet cover on side of engine.
2. Set piston at top dead centre on the
compression stroke. This will ensure valves
are seated.
3. Check clearance. Both inlet and exhaust
should be:
51cm (20in) machine:
0.10mm to 0.15mm (0.0039in to 0.0059in)
61cm (24in) machine:
0.08mm to 0.13mm (0.0031in to 0.0051in)
This should be checked by using a feeler
gauge between the tip of the valve stem and
the tappet on both valves.
4. If the clearance is less than the
recommended gap, remove the valve and
grind the tip of the valve stem with an oil
stone.
5. If the clearance is greater than the
recommended gap then the appropriate valve
or tappet should be replaced.
6. Replace tappet cover securely.
GB