It won't start with the decomp valve installed. However, there's fuel leaking from the head gasket so that probably explains why as the compression would be too low. Once the plug is wet, it won't go until it is cleaned with contact cleaner. Then with a few backfires, it eventually runs again. I could lightly flap disc the armature where the coil goes over to see if I can get a cleaner earth. Otherwise, the spark is too weak to support combustion. I guess the reason it will restart just after it has been turned off is the hot carbon deposits ignite the fuel & kick starts it until the spark can take over! A bit like a pilot motor on the old Cat bulldozers.

Edit: I've cleaned the armature and noticed it is spreading out at the back. Maybe this is the cause? I can't really fathom what the cause of the weak spark is. Cleaning didn't make any difference.
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Last edited by LRT; 22/12/16 08:46 PM.