Hello everyone, some time ago I bought a used Ultra Sport 60 with a Thunder Tiger 61 engine on the nose at a garage sale. Mind you-- It looks like this engine was sitting for a while, and I had to unstick the carb when I first got it. SO needless to say, it's not a brand-new engine. But anyway, I am at a total loss with this engine. It starts up great, but continuous running anywhere above about 1/2 throttle, the rpms start to drop and it will quickly stall if you keep it there. While I'm not an expert with glow engines, it seems like it's a little hot after it stalls, so the logical explanation is that it is over-heating at the higher speed. This would make sense because I have the high-end needle valve at only about 1 whole turn out. Ordinarily that would be really lean. However, it is spitting out a ton of fuel from the exhaust, so it would seem (to me) to be very rich. I tried switching out glow plugs for the heck of it and even some different props all to no avail. I would appreciate if anyone had any thoughts.

Thanks for your help.