Posted this in the Raptor section, but got no response, so I thought I'd try here...
Last year I bought a R50v1 with a TT50 engine. The engine ran OK, but never really developed much power even after the break-in period. I ran it on CoolPower 30% and the stock aluminum polished muffler. After about 30 flights or so, I had to lean it out to maintain the same power. I sent it in and Ace and complained of lack of compression and power and they replaced a lot of items in the engine no charge. They said they found an extra head shim that was causing the lack of compression. Well, the engine still had two head shims in it after they serviced it. So I guess they forgot to take out one of the head shims.
I took out one head shim and flew it for one tank after richening the main needle. It did fly with more power. So now I'm wondering whether or not I can remove the other head shim or not. Does the engine need at least one head shim? What is the recommended # of head shims?
Thanks in advance!