K&B .61 Ringed engine, low compression after running.

[jwvoth]

I have new cylinder, new ring, and just broke it in runtime 20 minutes very rich. AFter engine stops appears to have little/no compression. After cool down has some compress, on fast flip of propeller-but seems to leak on slow spin. Head bolts tight. Wondering, does ringed engine normally have lower compress, due to split in ring? Provided that head is bolted tight and no leaks detected around glow plug. Would a new piston help? ABC engines seem to have firmer compression in my experience. My address is jwvoth1@msn.com Engine seems to run fine, but not fully broken in yet. Plan to run at least 1/2 gallong and see how compression improves.

[MECOA]

I spoke with you on the telephone earily today, the ring may need to seat in and this may take up to 30 or 40 minutes of running. Ringed engines when fitted properly will have good crisp compression. On a ringed engine the seal is made between the outer diameter of the ring and the cylinder AND the bottom surface of the ring and the bottome surface of the ring groove. If the ring doesn't sit perfect on the bottom surface of the ring groove no amount of break in will help. Even a small nick, ding or score will prevent the ring from seating in the groove properly. Extra break in will seat the outer diameter of the ring if it does not fit perfectly when new.