RE: ZDZ80 SUPER
Up date on the ZDZ super 80 RV. Been flying this engine on a 33% Yak 54 now for 4 years. After figuring out the starting techneek, it has given me very good service. That was after replacing the stock ignition with a RCEXL ignition. The only issue I have with this engine is the cylinder is wearing at the top of the piston stroke. This is one of the black cylinders that is not susposed to wear. The piston ring was also worn quite a bit, and I replaced it with a new one. Now for the interesting part. Not thinking about it at the time, the cylinder never wore any, right where the rang end gap came to. The old ring simply followed the naterial wear pattern of the cylinder. The brand new piston ring when installed had less end gap, and rode up on the old endgap part of the cylinder. This effectley caused the piston ring to be unseated at the very top of the compresion stroke, dumping all the compresion at very critical time in the compresion cycle. For the first time, I had to use a electric starter to get it running. The new ring broke in enough after about 5 minuts of running to hand start after that.
Just thaught I would pass along this information, might be helpful to some one out there. These newer cylinders are not susposed to be wearing like that, but mine has. I have three China made engines that have ran and ran and ran, with no cylinder wear at all. All use the same gas oil mix, 32 to one.
Cropduster48