04 rm 125 cylinder questions

Aug 26, 2002
i rode my bike last weekend and felt a weird vibration on the engine so i took it to my mechanic and he tore the top end down. i only thought my bike needed a new piston and rings since i have used it maybe 20 hours 25 at the most with that piston installed.

turns out the ring broke a little piece and it got trapped between the pin that keeps the rings from moving, the ring groove and the cylinder on the exhaust side. now the cylinder is gouged and the dealer tells me to either sleeve it or get a new cylinder.

i was thinking about a big bore kit it might be as expensive as a new cylinder but i will get better performance.

so here are the questions:

What are the possible causes of the ring breaking?

does eric gorr still have 134 and 139 kits (i´m afraid the 144 eats up rings and pistons like the 144 ktm is doing right now) how many hours should i expect to go on the big bore pistons?

could i get the cylinder replated with nicasil or something similar and get the cylinder back to original specs?

thanks in advance for all your help.

Last edited:


Sep 25, 2005
Call Eric he can set you up how ever you like. Replate yours, bore, it whatever. You might even luck out and he'll have a good stock one come in. Best time to get him is in the A.M.
I might be a little cautious about debris in the bottom end though. Good luck.
P.S. we have an EG 144 with no piston or ring issues at all after 8 races and practice sessions