ok guys i need some help here. i have this xt2 for about 1 month now and after having to replace the one way berring and now it looks like ill have to replace the piston head. why because i believe its broken. i was running it just as i always do. i had it tune rich just so i can get it running for abet. all the saden car dies on me. i go to pull the pullstart and its hard as hell. i open the buggy up. and the piston is all black and locks up when it reaches the top as if the sleave got smaller? anyways everything inside seems to be working find. what happen did i ruined this engine or can i just get a new head and sleave?
please do help thanks.

you sohuldnt run your engine rich to get it to run, sounds like you dont know how to tune, if the top of the head is black i beleive thats from running too rich (or lean, i forget) if its hard to pull then that means its probably flooded (rich) and yes the sleeve is tighter at the top, this is called pinch, without it you would have no compression, also please read your post first, some of it is hard to read

na man its not flooded i have been in rc cars for 1 year now and i have a tc3 witch is tune for racing. no if you read carfully you'll see that the piston is locked. this is my first time a car as done this on me. i removed the sleeve and it looks find but the head of the piston is black.

i beleive the black buildup is from running too rich, what kind of fuel do you run, if its high in castor oil, this can happen

off my head i think its called trinity. another point i just remember is that it was dry there was no oil around the piston could it be that. remember it is hard when the sleeve is on it. its hard at top center. witch is odd because it doenst have its cooling head on. do you see what i mean?

thanks

there wont typically be oil just sitting on the piston, what you will need to do is very lightly sand the black grit off, only do it to the top of the piston, not the sides

im not to consern with the piston being black i'm consern that its hard when i but on the sleeve. to reach top (no cooling head on)

yes, i said that it was pinch, that is normal, since you dont have piston rings, that is how your engine makes its compression, all engines are like this, especially when new

My picco .27 engine head is blader then the ace of spades... runs fine, has been moded though, it does the same you are saying...it is NORMAL. I dont run my engine rich, nor lean, its probily from carbon buildup (burned fuel) and bured onto the head...dont rub it off, you will screw your piston head up...dont do it!

why would removing something that shouldnt be there screw your engine up, just remove the buildup, you oculd prolly soak it in some wd-40

I have been told that that was normal by a Very good modder that knows what he is talking about, he told me if i removed it, it would jus scrach the top of the piston up and screw up how the fuel burns ect. he said it wont run the same again...He knows because he has been into modding motors for years and knows what everything on the engine is and what that black crap it, so if you decide to remove it...so be it, just telling you the facts...

Dude HPI APollo is absolutely correct, the sleeve is tapered and expands when it gets hot and you acually loose compression if you overheat your motor, then the sleeve contracts again as it cools and you will notice compression again. I understand you have been in this hobby for a year now, but I am 40 and have been involed with models since I was a kid, and I go here for help because I still learn something here everyday, just give some veterans the benefit of the dought and you will be happier when you model runs right. Black ontop of you piston is normal, its burnt castor. try closing your bottom and top end a little then try again. there is nothing worse than having a motor run bad. Well I can think of a few other things but thats another topic...

talk to Fuelman, he is the one that has told me fine grit sandpaper works, try WD-40 to dissolve it

ok people wake up time. i toke the car apart yestrday night all the way out. meaning i stripped it out of the engine .i notes a missing piece. on the piston the sleeve is screwed! ill have to get a new piston and sleeve. that was no normal pinch where talking about this was hard has hell. that is not normal lol. the sleeve is damage from the piston.

how could that happen? your not suppose to push the piston through the sleeve....did you do that?

im thinking that you guys are not understanding me my choices of words maybe off and not be best to explain. none the less i did buy a new piston and sleeve! i installed it last night. all i need to do now is go to the park and get this baby up and running agian i also talked to the LHP as to how this happen. he told me i was running to lean. or WOT to much. and it just was to much heat to handal. the piston and the sleeve where burn behond what would be normal. as he explain.