I'm having trouble with my TT46pro with #8 OS plug Tower muffler and 9-7 apc prop. It's always been a very reliable engine but lately it looses power. At start up it runs at 16000rpm but about 1 1/2 to 2 minutes into a full throttle run it looses power and goes down to 12000rpm? This is bad because I start up taxi out take off and 2 min later it's running weak and a little while later it dies[X(]. I've checked my fuel system and replaced all tubing. I've replaced the carb. All I can guess is maybe the bearings are bad and when it heats up it has some resistance. Is there a way to tell if the bearings are bad without pulling them out? If I'm going to go through with bearing removal then I might as well replace them. Compression seems good. Any help would be greatly appreciated. Deltatech

You can spin the crank between your fingers while feeling for roughess. You can listen to the engine for a roughness when you flip the prop.

Try setting your engine a little richer before take-off.

Enjoy,

Jim

It sounds like it is overheating in flight. Turn the main needle out 5-6
clicks more and see if it still slows down. Some engines have to be
started out real rich....richer than you would think.

FBD.