Racing this saturday just about to hit the 117ft table at our local track roughly 4th pinned my bike made a a huge BANG and came to an immediat stop only to realize bike was seized and oil spewing every where!!! the piston has 25 hours on it, vlaves check and adjusted when needed every 15 hours. should be interesting what caused it more pictures to come!! If any one has engine casesfor cheap let me know!!! might consider selling my 4000 dollar pro action suspension, many other spares for to buy the new rmz as i was going to buy one anyways and make this a practice bike let me know if your in need of anything!! have tons of spares!!!
Took engine out!


FOUND THIS IN MY SKID PLATE


What ever broke that from the inside did some damage

I would cry.

This is a great 2 stroke campaign!

Kidding aside...sorry man, best luck might be to find a used 07+ bike and swapping your components onto it and selling left over parts to help with costs.

looks like crank failure.....mine just let go @ 50.5 hrs on the meter.

yeah thats the bike i bought i was crank failure haha i got a new hot rod crank assembly for it and welding the cases and new piston and bearings for it itll be sweet soon the inside of the case is gouged a bit but just sand it down and itll be good

Ouch! Sorry you experienced that! Glad I just had my crank rebuilt (Mr. Crankshaft).

Thats DEFINITELY a crank failure, if you don't mind me asking, how many hours did the bottom end have on it?

Our first crank went out at 18 hours... thank god that did happen

Crank had 50 hours, and was getting changed soon! I have pictures on my cell phone of the piston cracked ect. Valves were fine, cylinder would need  a re hone (I'd put the 290) instead! Just going to get the 2012 in a month or so! Also I blew up both mine and my sisters rm 125s! One wiseco piston with 5 hours cracked! And ruined cylinder pretty good and then I Seized the bottom end bearing on my sisters bike

you must be pretty fast (or rev the piss out of them) to be going through bikes like that!!! what class do you ride? i had an 09 rmz250 with almost 100 hours before changing the crank (it looked fine when i took it out too) the 2011's got an updated crank which supersedes the 2010 in the part numbers, whether its better is anyone's guys for now...

P.S. your gonna love the 2012

2 stroke are ment to be revved to shit and your supposed to change the piston every 4 hours of racing, i have darrens 09 with the blown up crank the valves werent touched cases are thrashed but theres nothing a little tlc and maching cant do i ordered new crank and main bearing piston and gaskets and it should be running with in 2 weeks

and another reason it blew up is because it was coleton mcleans arena cross bike

03cr125r said:

coleton replaced crank, piston ect. right when i bought it. the valves and everything werent harmed already knew that. the bike does have the acclerator pump mod in the carb, definatly helped! i only raced it for 3 rounds before i shattered my wrist, and 5 rounds before i went to school at BCIT and raced 2 rounds before it blew up this year. hrldy rode the thing to tell you the honest truth. the steel braided line was was a good improvment. rear shock was just serviced right before it blew:ride:keep me updated on it!

the samething happend to my 08 rmz 250 but it took the whole head with it. lol

I have an 08 Rmz 250f as well and after 40 hrs had to replace whole bottom end