I've bought my first four stroke engines, after having flown helicopters with two strokes almost exclusively. I'm not entirely sure how to tune them, or break them in. I'm familiar with ringed engines, and bought a TT 54, and a Magnum 61 for my first four stroke victims. I'd like to run coolpower 15% heli, or perhaps powermaster 15% (the castor alternative).

How do you tune a four stroke? With a tach, but where do I start. The TT 54 will not hold anything above 3/4 throttle very long, regardless of needle setting. The valves are adjusted correctly. How do I tune the low end needle? Can you do the pinch test like a two stroke? Your help is appreciated.

I can't get this engine to hold anything near full throttle without dying immeadiatley. No transition. How do you set the idle air bleed? Do you start all the way in? It acts lean, from what I can tell. I have opened the needle from 1-4+ turns with little change. It will idle okay at a high idle, and then when you give it gas it will speed up for a little while, then die abruptly. Any ideas

It almost sounds to me that you might be a little rich on the low end, but too lean on the top end. When you idle it could be loading up which would allow you to run at higher throttle for a short period, then the lean top end would cause the engine to die. I don't know you might try making the high end rich first and not worry about the low end until you get the engine running reliably at full throttle. When you throttle up the engine, do you notice it making smoke, then does the smoke go away before it dies? If you lose the smoke in your exhaust before it dies, you are most probably running too lean on the high end needle.