Robin. There a engine that wants to run at a high RPM and use a low pitched prop. 12.5x3.8 APC at 10300 would be a good starting point. ALSO ADD a head gasket .005 use a hot plug. Low Nitro (5%)with 50-50 18% oil with TWO-Four ounces of Castor added per gallon. The muffler is the question. I used the Mac's Black MINI PIPE...works very well. Other then that I ran that engine about 50 times and was offered $$$ so I got rid of it. IT WORKED! I used the other smaller leo 34 in my profile cardinal, and I use an leo 15 for clown racing

Hi Robin,

I have a Leo 46 that was given to me. I believe its very close to being the same engine as a OS46SF. The venturi is very small on the leo and seems to work okay, (never checked the size of it) the engine is okay, runs well but not as well as a good old LA46. I don't believe anyone has tried this engine on a pipe, might just be a winner with that type of set up. Mine will 4/2/4 but it really like to run hard, which isn't really good for stunt. Mine is build very well and isn't junk but again the OS 46 LA is a better motor for stunt??? Got to remember what works well for one doesn't mean it would work well for you. If ya get it, play with it and let us know how she worked out for you. I also found that my Leo like 5% or 0% better than 10%. Mine swings a 12/6 apc prop and doesn't miss a beat and she is flying a sixty size ship with out a problem??? Good luck, Gary

Hi Scott, How did you set up your LEO 34? Do you like that engine?  Thanks, Mike