I purchased a Tower Hobbies .46 size engine from a fellow rc'er. It runs just great at full throttle and always statrs flawlessly. My problem is that you have to let the engine load-up to die. I have the carb barrell set where it COMPLETLY closes and it still runs. He had another .46 size engine he bought from tower hobbies scratch and dent forum and I bought it too. I have the same problem with both engines. My only guess is that it's sucking air somewhere? You can put your finger over the carb hole and it still runs! (I've tried 2 different carbeurators). I've checked the fuel lines, the engine's backplate, and all the seals. Perhaps its sucking air at the crackshaft bearing? Can anyone help me get my engine working correctly? Also, would the low end needle setting have any effect on this? Where would be a good starting point to set it?

You might first try to check for leaks around the carb. Check the o ring etc. Or maybe you could try richening the low speed needle a half turn or so.

FYI - some of the GMS engines have a problem shutting off also. Some have discovered leaks around where the carb fits into the crank.

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I don't think that just buying another engine is the answer. I have the exact same problem with my Irvine 46 (which is a quality engine) and everything is tight. I've had the engine apart and the front bearing appears solid (i.e., no air leaks) and no leakage past the needle valve either (the O-ring is installed). I've checked all the 'classic' leak spots (carb, etc)

I'd also be interested in knowing if anyone has had a unique solution to a problem like this.

Regards,

Bob