1QwkSport2.5r

The 60-4C does not need muffler pressure, but it will work fine with muffler pressure if you have a muffler on it. I have a 60-4C myself and I've found it to be a very good running and reliable engine. However, it likes a fat idle mixture. It will be a little blubbery on transition, but it rarely quits. This is running it without muffler pressure. I run mine on 5-10% nitro 20% castor - keep the nitro limited to 10% or less. It doesn't run any better and very little faster on more nitro. I set the valve lash cold pretty tight - .001" is all that's needed. The lash gets wider as the engine warms up. The prop shaft is 7mm X 1 so any Dubro or Sullivan spinner nuts will work. I have a Higley jam nut (thin flat lock nut) behind the spinner nut on mine. Enyas like to rev, don't be afraid to let it rev to 11-12k. The carb will spit a lot of fuel if it's over-propped. Max revs is 13,000rpm.

Lastly, the fitting on the back of the crankcase is for venting oil out of the crankcase. Run a length of fuel tubing from the fitting outside the fuse.

Use a tach to set the main needle, it's pretty tough to hear when a 4-stroke is at peak revs. Usually it will just quit if you get too lean, but it might backfire and kick the prop off if too lean on higher nitro fuel. If you don't have a tach, start it out really rich and lean it out until it just cleans up and runs smooth. An occasional misfire is fine.