If you have a lot of runtime on the engine, it is possible the piston isn't as snug as it used to be. Even though a previous engine didn't do it, that could be because of a slight variance in break-in, or simply motor contruction tolerances were different.

at first thats what i thought it was,but it still has lots of compression.

Even when hot? Really weird then. Something like that happened to me once and it was a leaky exhaust coupler that looked good. But I'm no nitro expert, lol.

i'm not a nitro expert, but i can tell if the coupler was tore.

Are you saying that you guys have been running the same engines for three years? If so, you're doing pretty good. I could tear up an engine in two months, or less.

If the engines are that old, I'd pull the carb and make sure that the o-rings are sealing. For some reason, more air than is supposed to is making its way into the engine.

Have you pulled the head to make sure that the gaskets are sealing? When you say that there is good compression, did you try turning the motor over with the plug removed? Are you sure it's compression that you're getting and not pinch?

I don't know, I'm just throwing things out there. Trying to diagnose an overheating problem without seeing the engine is like calling a mechanic on the phone and trying to describe a noise to him.

no. we have had the trucks for three years. together we bought about 10 engines.

I gotta agree with serum, for the price of those 10 engines you cold have bought a couple of quark/neu combos, a HUGE stack of LiPos and wouldn't be wasting your time fiddling about with glow engines that don't run right for no apparent reason.

Sounds To Me
 

like you need to clean your air filter, if it can't breathe she gets mighty hot

Actually, I would think that a dirty air filter would cause a rich situation. Too much fuel and not enough air.

naw
 

your carb decides that, a clogged air filter is like choking someones neck, watch how hot and read their head gets!

Wait a minute. That's a dumb ass comparison. Sorry, but I just had to say it. Choking someone has nothing to do with the temperature at which a two stroke internal combustion runs.

Barring any binding in the drive train or clutch or excessive running over tall grass or similar terrain, the temp of the engine is controlled by the fuel air mixture. The richer the mixture, the cooler the engine will run. The leaner the mixture, the hotter it will run.

Given any particular needle setting, choking off the air richens the mixture. A dirty air filter will richen the mixture.

sorry for the dumb ass comparison
 

but you don't tune a 2 stroke internal combustion engine with the air filter, you use, first the high speed needle, then the low speed needle, and if it is too rich or too lean only the carb adjustments will correct it, a clogged air filter can cause hot engines because of restricted breathing, i was just trying to be funny and give the guy something else to check so he could run his t-maxx with his dad, as I run nitro's daily and am trying to expand my r/c knowledge on this brushless forum and help where I can, how does negative criticism (dumbass comparison) help anybody??? Aangel you're usually so helpful!! Can't we all just hit a b?ng and get along!

oh yeah
 

notice the 4 inch k&n air filter on the t-maxx in my avatar? it is really an automotive oil breather, i got sick of the little stock air filter getting clogged and my engine running hot, so I upgraded and keeping my k&n cleaned and lubed really helps my temps stay stable

OK, sorry about the "dumb ass" comment. Your experiences are your experiences. I just disagree with what you said.

my tmaxx is fine, its my dads that is getting hot. but it might be the grass, because when he takes it to the track, he can go through a 5 lap race and it wont get hot as fast.