Is there a pin on piston where ring gap has to be.... my stock raminator engine has one. The damage looks very familiar as in the stock raminator engine l overheated because it was lean, almost exactly the same. I have not had any problems with my zenhoa 5t to have to disassemble so I'm not sure about the ring pin .
Losi 5T Multiple Cylinder/Piston Failures
- Thread starter Rockfootball47
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Any engine that has transfer ports , intake or exhaust in the cylinder itself needs to have a pin for the ring so it does not rotate, otherwise it will hang up the end of the ring in one of the ports.
We do not have this problem in 4 stroke engines since the bore is smooth it doesn't matter where end of ring is.
Well it actually does matter but for different reasons and a ring getting stuck in a port hole is not one of them
We do not have this problem in 4 stroke engines since the bore is smooth it doesn't matter where end of ring is.
Well it actually does matter but for different reasons and a ring getting stuck in a port hole is not one of them
Oh yeah, that was before the pictures. Something broke free and mutilated that.
If both of the clips on the wrist pin are good, check the ring locating pin.
Rockfootball47
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Wrist pins are intact as well as ring locating pin. The very first issue I had last year was the result of the locating pin coming loose. I’ll add a picture below. But after that, I replaced the cylinder and piston, ring, wrist pin and roller bearing. Failed again, then I completely tore down and cleaned, and replaced piston and ring only. Then this last failure.
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Yikes! what ever the cause, some of the metal is definitely down in the case still. Was the piston ring completely gone also? Any scaring on the crank shaft body? That's too bad this happened.
How long did it run prior to the nuclear meltdown?
How long did it run prior to the nuclear meltdown?
Rockfootball47
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There was definitely quite a bit in there after the first failure because the crank wouldn't reach BDC when I was reassembling it. I sprayed it out with degreaser and then blew it out with some small debris coming out. Apparently I didn't get everything because it failed again. After that second failure, I completely disassembled and cleaned the crankcase. Then it had the worst failure yet of course lol. Short of the debris being in one of the side ports and me missing is, which I know I blew out and looked at after the second failure, I have no idea where the debris came from.
The only failure with any damage to the ring was the first where the ring gap was worn larger since the pin came out. The end points were still intact, but the cutouts for the pin were larger.
No scaring or damage that I could find on the rod or crankshaft. All of the roller bearing pins are present and undamaged also.
As far as the last and worst failure, it ran for less than an hour and most of that was breaking it in.
This engine is just dead to me lol. I'm cutting my losses and buying a new one and keeping it for spare parts. I was debating on upgrading to a 46cc, but that'll be a future project.
My guess is a needle bearing judging by the imprint. Only way to find out is to split the crank. Did you use the same crank with each rebuild?
Well I honestly didn't think of this , personally never saw it on a 2 stroke but have seen it more that on roller lifters in a V8 more than once.
Great thought.
I am wondering without a crank in front of me is " Can you see the needles without splitting the crank'?
There is a crank on my bench and now I will be looking to see when I get home later.
@smokinwheel I agree and I feel like its a plausible theory but at the same time I'd expect to find unfavorable movement at the crank side of the rod. It looks like the cases,crank, crank bearings are being reused through these rebuilds so I can only suspect the crank and crank bearings at this point 
It's a headscratcher for sure. Now I need to look later at a crank. #1) to see if you are able to actually see the needles when assembled and #2) is it possible for a needle to even make out from the big end of the rod when it is assembled.
Wrist pin needle? There are a bunch in there as well. Just another dumb thought??
Wrist pin needle? There are a bunch in there as well. Just another dumb thought??
@smokinwheel I 100% agree with that too 
, im not sure if and how a needle can slip out but at this point im looking at everything. The small end of the rod tho i figured the op would notice as he's been changing those but the issue continues to follow him.
, im not sure if and how a needle can slip out but at this point im looking at everything. The small end of the rod tho i figured the op would notice as he's been changing those but the issue continues to follow him.Not sure a needle from the wrist pin could slip out either ; just my scrambled brain thinking???@smokinwheel I 100% agree with that too
I need to look at a few things on my bench when I get home later.
Don't want to side track this but I am going to PM you , you do race Wagner park don't you? I picked up some onroad cars and looking for places to go.
Back on track here , Thanks