Broken Piston...
 

so i recently rebuilt the top end of my recently bought 82 g1; bored cylinder, new piston, rings and all the lil ends and outs. ran great for a few weeks then all of a sudden no compression! popped off the top to find the groove that holds the rings broke off and shattered rings. called my supplier but no word back... was wondering if anyone else had this problem?

Re: Broken Piston...
 

Face book won't open the images.

Did a ring hook the exhaust port
Did you
rechamfer the edges of the ports
allow a little extra ring end gap for the over bore

Re: Broken Piston...
 

yeah sorry about that i wasn't sure how to upload pics, but i don't have a boring bar so i took it to my local racing guy. i assume he did everything necessary for boring it out. i left the head at the shop and will have to take a look at it in the morning to look for the chamfers. how much should the edges be chamfered?

Re: Broken Piston...
 

Not much, just to get the casting flash off. When you buy a new jug kit they usually come from China, not nearly the quality that the orig Yamaha part had. With that said, it must have been a defective piston. These things can have cracks from the factory, I've seen it before with Kawi parts. Unless you spend the cash on Japanese Yamaha parts, it's kinda a crap shoot unfortunately. Hopefully you bought them from a site sponsor? or at least a reputable company? If so, they should work with you.

Re: Broken Piston...
 

Gilbert Golf Cart is who i went through. talked to them today and the said i have to ship it back and then they will ship back to manufacturer (nivell? they are behind buggies unlimited if i heard right) to check to see if it was defective. then they will credit me back the money if they find it defective... total time 4-8 weeks... i looked tired looking, were can you find authentic Yamaha pistons and rings in a .75 oversize?

Re: Broken Piston...
 

oh and checked the cylinder doomsman and all the ports are chamfered.