Originally Posted by hsukaria

I have a question about a GX/AX-40 engine I own. It is very draggy when turned by hand. I checked and it is not from rubbing against the backplate. I suspect that it is the tight fit of the piston to cylinder. It has about 2 liters of gas mix run through it. The extreme tightness of the engine due to friction has me worried. I bench ran it as an AX-40 (glow not gas) on 15% nitro, 15% castor, 5% synthetic oil, 10x6 APC prop and I got 12000 rpms at WOT. So the performance is not bad, but the friction has me worried. Also, I found out that the backplate was slightly loose even though I had tightened it real snug before running it.

Any advice or ideas if this is a problem or just run it the way it is?