ORIGINAL: cutaway
If its doing this, then your engine is completely worn out.
I reached that conclusion on my own... That is why it is being replaced.
ORIGINAL: cutaway
What fuel were you running in it?
different fuels... in the 10 to 15 percent nitro range.... sometimes with added oil and sometimes not. However, I dont think its the fuel. I bought the engine and plane from the local clubs "fly it till it can fly no more and then some" guy... He does not take good care of his engines