Need help! Got a ZDZ 40 giving me problems. 1st it was surging really bad at full throttle. Ran fine at idle up to mid, but any higher and it started surging. I called RCS they said the surging was from a lean mixture, so I fiddled with the needles, but never could get it to stop. So I changed engines and now, need the 40 for another plane. I took it out and put it on the bench. Started fine but had a clicking sound when running and threw the prop braking the prop bolts. There doesn't seem to bee any slop in it at TDC, and has good compression but I can't help but think it is the rod making the sound. This engine has been problems since I bought it new. The ring broke during the 1st month I had it. Then the surging, and now the clicking sound. It is out of warranty and I really hate to send it back to RCS and have to pay more to fix it. ANyone got any ideas?
I realize that this thread is quite old, but if you still have this engine, I might have a cure for you.
I have a 40 RV that had the same problem with clicking noise.
I gave it to a friend of mine who dismantled it and found the combustion chamber full of carbon.
He cleaned it up, put it back together and it runs great. He mentioned that I should run the engine at a 50-1 gas-oil mix, as 40-1 is too much oil.
Hope this helps.