I run an Evolution Engines .46NT on a SIG Kadet LT 40. I've flown the plane twice and the engine has less than 1 hour of total run time on it. I'm using the following fuel:

Ultimate Fuels, 15% Nitro, Castor/Synthetic Blend 17% Oil 20/80. I am also using a three blade 10X7 Master Airscrew prop on it. The other day, I flew the plane and after 4-5 minutes of flying, I heard the engine "bump". It skipped for just under a second. We brought the plane down and I have not flown it or had a chance to check the engine. I am a newbie after a long hiatus from the flying sport. Could someone give me some ideas about why the engine might have skipped? Does it sound too lean? I had an experienced pilot lean it. It ran OK on the previous flight. I do not see a lot of exhaust coming from the muffler when I run it up. To me, that signals too lean, but that's just me talking. What do you think? I heard many good things about Evolution but I am now wondering, should I have bought an O.S. .40 or .46 instead? I just received a GeeBee Tach. Perhaps I should run it all the way up and back down on it as a first remedy?

Help,

Phillip
http://www.sandhillsrcflyers.org
Lavernia, Texas

I have that engine. I would guess that its a combination of being over leaned and over propped. A 10x7 2 blade was the biggest 10" that mine was happy with. I would suggest using more like a 10x4-5 3blade, or an 11x5 2blade. that should give you better static thrust also.