I bought a used plane and engine from a fellow flyer. The engine is a Thunder Tiger 91. Last night I was ready to start the engine to see how it would run. After a few needle valve adjustments and throttle adjustments the engine started. It sounded real good at idle and up to half throttle. But when I advanced the throttle beyond half throttle the engine sounded like it was going to come apart. A large rattling sound. Any ideas? If I wanted to get the engine looked at for diagnostics, what and where would be the best place for that. I am not confident enough to work on the engine myself. Any help would be appreciated.

I have one, the cam wasn't oiled because the wrong bearings were installed from the factory. Take the cam cover off the RH side of the engine and check it for oil. If you find metal in there, you have problems. Also pop the rocker covers off the top of the head and check for excessive slop in the rocker arms. They should be just a tiny lose, but NOT lose. Use a piece of paper under the rocker to check it.

Hope you dont need parts because Ace Hobby (TT distributor) closed their doors last friday.

TT's really can carry on when they are too lean on the top end. They are also well known for shucking props when lean. Richen it up quite a bit on the top end and see if it doesn't smooth out.