Brand new motor broke rings

richirich

richirich

New Member
Is it possible to have just had a bad set of rings? Yesterday , i got my motor all put together put gas in it and went to start it up. it fired right up and was idleing perfect so i took off around the block , them motor was sounding real sweet. i was only about 1/4 throttle then about 1000 ft down the street i hear this lound matallic snap. i instantly pulled in the clutch and pedaled home. I pulled the head off and tryind to turn the motor -no go, so i pulled the jug which was a little hard and what did i see. the rings are broken and where the rings snapped there is heavy gouging on the piston but no scoring of the cylinder wall(thank god) The rings were on right ,i can see the bevel lined up with the ring stop. the needle bearings are all there. i was running 20:1 castor 927 oil -which everything looked well lubricated.
The piston is totally toast. ive been going over everything with a fine tooth comb and just cannot for the life of me come up with why this could have happened.
Any ideaS WOULD BE WELCOME

but the worst part is since the the order for new parts on friday which means they will not arrive till next wendsday :(
 
Broken rings in these HT engines are not that common, considering how many are bought and installed. BUT, broken rings as far as I'm concerned by different posts are all too common comparing to other manufactured engines.. I'd bet that the rings were broken upon installing them from the factory. Do NOT install a piston/rings that the piston is missing the alignment pins.

While you have it torn down, you might think about inexpensive modifications if you haven't already done so. Make sure that the rings are installed correctly. Note the ring alignment pin in the ring grove.


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Well after a little more studying of the piston i discovered that the gouging on the piston on 2 sides line up with the transfer ports so maby it wasnt the rings but something through the transfer ports. but what is weird is the gouging is almost identical on both sides of the piston. Any ideas on that one?
 
i think i figured it out, upon more inspection of the cylinder i found some chunks missing from the walls of the transfer portss. it must have been some casting flash that had broke loose and destroyed everything.
oh well, back to the drawing board.
 
richirich said:
i think i figured it out, upon more inspection of the cylinder i found some chunks missing from the walls of the transfer portss. it must have been some casting flash that had broke loose and destroyed everything.
oh well, back to the drawing board.
Click to expand...
Should be covered by a warranty from the seller but good luck on
getting a new motor or even the replacement parts.

Where did you buy the kit from?

It really does pay to at least remove the head and take a look inside
to see that there are no problems or even pieces of metal from the
sparkplug threads, etc before you fire a motor up.
As we all know the "quality control" is not to be trusted......

Do you have some pics of the transfer ports?
 
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it was a brand new motor , i broke off a exhaust stud over tightning it .So instead of messing with it since i wanted the MM high compression head i just went ahead and ordered a new cylinder. well like i said upon inspection i noticed chunks of the transfer port clost to the piston missing. im sure it must have been casting flash that had broken loose. ive read in other threads that this sort of thing is possible. it destroyed the piston and rings. some how the cylinder is not scratched but with the pieces missing i dont think i would want to use it. the motor and parts were purchased from piston bikes so this morning when they open ill see how how good they treat their customers. ive never seen bad revuiews of them so i dont think there will be a problem.
The worst part is i want to ride my bike aagghhh
 
richirich said:
it was a brand new motor , i broke off a exhaust stud over tightning it .So instead of messing with it since i wanted the MM high compression head i just went ahead and ordered a new cylinder.
Click to expand...
So you took the cylinder off a brand new motor and replaced it
and reassembled the motor?

That would not be covered by warranty because who knows what you
did to it?

Do you have some pics of the damage?
 
yea i boke a stock exhaust stud i guess from over tightning it so insted of messing with it i just ordered a new cylinder with the mm head. i cant get a good picture down the cylinder at the transfer port but you can definatly see material missing on the angle slope towards the piston and it matches the gouge that starts at the top ove the piston down to the seconed ring. the other cylinder head is not missing any material and way smoother. I think the repacement cylinder was just poor quality
 
heres pics of the cylinder and piston
 

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