The OS LA series
I like my OS .40 LA, runs like a charm. In fact, when i first pulled it out of the box, and fueled her up and tryed starting her, it fired on the first flip and scared me making me drop my stick into the prop which quickly stalled the engine and ruined a prop. Now 4 years later, my engine still runs strong and halus a lot of ass. I have had to do few repairs to this thing, only change the plug twice, replace the head once because i stripped the threads out, other than that, just clean it out each season. This is the engine that i have used to run many experiments for alternate fuels, and for performance inhancers. A few of these have been direct oxygen injection into the carb, direct nitrous oxide into the carb, running hybrid fuels of glow/gas, glow/naptha. None of these would be practicle of course, but neat to push the engine a little, i don't think OS ever designed this thing with 21,000+ rpm in mind while spinning an 11x7 prop. It is a nice little gem for under 100 bucks