The compressions on my DL has not been good enough. The engine has abut 60 flights on it. It is quite easy to flip the prop over. The high RPM can reach 7000 on the ground with a Vess 22B but in the air it definitely does not deliver the punch.

Since I was thinking about replacing the ring anyway, I too the cylinder off. On examining the ring, I found there are several dark sections (aka ridges) on the exhast port side. It could be that the corresponding areas on the cylinder wall are not consistent and there is no chance for the ring to seal well. The anti-rotation pin on the groove of the piston is very tiny (compared to DA's) and the ring has about 5mm of rotation freedom.


Another problem is that boh threads on the cynlinder for muffler got stripped and muffler came loose during the flight, which happend yesterday. I would think it was caused by vibration?


So looks like some parts in my DL are not up to the standard?