rust on spark plug diode

[scally scouser]

hey guys am just finishing tri-z rebuild, frame an plastics r done an now am onto engine

when i took spark plug out their is rust on the spark plug diode now the person who i bought it off said it had recently had full engine rebuild but 1 ov the problems with tri-z when i bought it was that the power band would not kick in all the time only sometimes when it did kick in it the trike wud move like it was suppose to so am assumeing the head gasket aint blown cos it werent loseing water i read sumwere that it could be water in fuel

as anyone come across this kind ov problem before ?

[RubberSalt]

Check for an air leak. You need to do a leak down to do this.

Basicaly, your going to pressurize the engine. pull the exhaust pipe, plug the exhaust hole. Put the spark plug in, and then make a leak down tester to fit your carb boot. Basicaly a plug with a tire valve in it. Pressuirse the bottom end with 7psi of air. spray soapy water all over, make sure it doesn't leak. If it leaks more than 1psi in an hour, it has a leak thats not fun.