BobV1700

I have a 35cc MVVS gas engine that's only had about 4 hrs running in total and is still slighlty rich. I'm using a 1:40 oil/petrol ratio and the engine appears to be running well but the exhaust residue is thick, black, and has a sticky consistency. I am I right in assuming the residue is caused by the slightly rich settings still? The plug is a nice 'sand' color with no significant oily coloration and I'm using a high quality spec 2stroke oil.


Thanks Bob V

cymaz

Sounds correct...I am running in an engine on 20:1 in the plane. I have spots of black all over the bottom. At 32:1 it's not bad at all.

planenutzz

I have a MVVS 30 in a 1/4 tiger moth, been flying it since 2011, loads of hours on it. 30:1 synthetic and have always had black, thick residue.