thanks for the reply XJet.
basically everything you said is what i am using with the engine and i recently dismantled/cleaned the engine there is no sigh of wear. the only thing that you suggest that could be the problem is the fuel which has 10% nitro. I used to use 5% nitro and i think i found it to be pretty useless thats why i changed to the 10% but that was about 2 years ago.

EDIT.

Just checked the specifiaction of the fuel im using. its 8% synthetic oil and 2% castor oil. Is this killing it?