broken rings

[swmichsx]

200 miles ago i rebuilt my top end. everything was checked and well within spec. yesterday my sled broke a ring and trashed a cylinder. i used brand new pistons , rings and gaskets. they ere the SPI ones. my sled is a 97 SX 700 and the bad cylinder is the mag side. just wondering what might have caused this?

 

[9801srx]

did you check the ring end gap before assembling? some times rings need to be filed to get enuf end gap,with out enuf the ends butt together when they get hot and break.

 

[swmichsx]

yes i did. i filed them myself and constantly squared them in the bore to check. the other 2 cylinders are fine.the were installed correctly as well.

 

[redrider24940]

know your pain Bud. Seen ya on my thread. I will keep ya posted on if I find anything

 

[swmichsx]

thanks

 

[crewchief47]

The ongoing rule of thumb here is to use OEM parts if you want reliability. I know that doesn't help you in your current pickle, and it doesn't explain what actually happened, but it may help alleviate future pain.

 

[swmichsx]

i know. i will be using yamaha rings on all three cylinders when i put it back together. i have heard that the SPI pistons are good but the rings suck!!! i believe!!!!!!!!!!!!!!

 

[snowfoxsx]

same thing happened to mine with spi kit

 

[swmichsx]

same thing happened to mine with spi kit

when you put it back together what parts did you use?

 

[YamahaSXR700]

my brother put some SPI piston on hiis tcat1000

 

[mopar1rules]

you say you broke a ring.....did the ring stop pin back out, causing the ring to spin and catch/snag the exhaust port, causing the beakage?

 

[swmichsx]

i will look right now!!!!!!!!!! nope, the pin looks just like the the ones in the other 2 cylinders. the gouge marks are actually on the intake side.