Blew The Top End

micah1234 · #1 (**permalink**) 05-04-2008

I put a newer piston in my bike but not brand new, i rode it around for 5 minutes and the top end blew up, the bottom end still shifts and the clutch works but the kicker is jammed, What did i do wrong?? Is it gonna be a bitch to get the top end off?

Thanks

89shee · #2 (**permalink**) 05-04-2008

man that sucks you might of got a ring jammed. wre you ripping on it? or just putting around?

lt250racer · #3 (**permalink**) 05-05-2008

Was the piston even the right size? Was it a smaller overbore?
I have lerned my lesson in the past, I will never do another top end with out replacing all moving pieces with new parts!

You are going to have to take the top end off & inspect what exactly happened.
Dont kick it anymore because your most likely shoving part of a folded ring into the cylinder. Depending on how messed up it maybe, you might need to get the cylinder resleeved if the grooves are deep enough...hopefully not..

Time to get the wrenches out.

climb any hill · #4 (**permalink**) 05-05-2008

If you blew a hole in the piston then you prob have debris from it down in the crank area.
Do Not move that kicker. Gotta pull the top end off to see what happened. Post a list of your mods & jetting for these guys to help you.

Was everything torqued down?

micah1234 · #5 (**permalink**) 05-05-2008

today i took the top end off and there was a nice gash going down the piston, and inside the cylinder. so im guessing there was just some debry in there.So i went over to my buddy's house and bought a complete parts bike from him a 1992 rm125 2 years older than mine for 400 bucks, took his top end off , slapped it on my bike and now it runs great, thank god it didnt bust my crank.
Im gonna sell my bike along with the parts bike. what u think it will go for??
my bike- 1990 Rm125
Boysen Pro Series Carbon Reeds
Procircuit with fmf silencer- lol
Renthal Gold chain
All new plastics
New graphics/seet cover
sand blasted/ new paint on frame
Black Pro Wheel Rims
New tires
New EBC clutch,
New showa forks
did have a Wiseco Piston to i blew it haha

89shee · #6 (**permalink**) 05-05-2008

it really all depends. i sold my 94 rm for 700 and that ran like a raped ape. a friend than bought a 98 yz for 450 bucks. so i guess it depends on location location location and shape of the bike.

lt250racer · #7 (**permalink**) 05-06-2008

Why are you selling??
I would guess around where you live, A good price would be around: $500-800

micah1234 · #8 (**permalink**) 05-06-2008

Today I went riding once,again i was taking it easy and the bike just stopped, So I went to Kick it and it was Jammed....... SOB!!!! I flipped, So once again i blew the top end. Why would the same exact thing happen. I followed the Repair Manual exactly, and every thing was right. Why would i blow 2 pistons/2 Cylinders in 1 week after they run perfectly fine, So now i'm probally gonna part it out, I want to sell it because i want a bigger bike. However would it be worth getting it bored out and just keeping it?

Thanks

lt250racer · #9 (**permalink**) 05-07-2008

Well something is always at fault when the topend goes....
You need to find that fault, Redoing the top end is only part of the answer.
Its most always in your favor to redo the top end. A running bike is always woth more, Just weigh your options.

By the way....Two strokes Usually run great just before they blow....