piston burned and sleeve cracked

[kx250.1698]

Hi guys need help please!!!!

I just freshly rebuilt my engine at the bike shop and ran about 3 miles and piston burned at exhaust side not on top. And sleeve cracked.

What could be the problem of that???

[KX500freak]

that sucks ..

did you start the break inn cycle correct ?
that means no revving at all in the first miles ,just gently twist it for a quarter ,no more ,
let it cool ,ride it till half throttle,let it cool ,ride it gentle to wot the last cycle

[kx250.1698]

I just freashly rebulted my enjin at the bike shop and did run about 3 miles.piston burned at exast side(where you could see pistin) not on top of the piston. And sleef9cylinder) cracked.

What could be the problem of that???

[keithluneau]

As to the problem at hand, I'm not sure why it would burn up so quick! I would guess that either the wrong oil was used, not enough good oil, maybe the sleeve was defective, installed wrong, the engine wasn't broken in properly, it could be a lot of things. It's hard to say without seeing it first hand, and knowing all the details!

[hughes]

Cooling system failure. If the top end was just rebuilt then the coolant had to replaced and proper bleeding of the cooling system is very important. Maybe the engine overheated and failed.

This is related to the kx500 but I think your bike is the same. Check out photo.

[kx250.1698]

The bike did overheat jes

[Danger4u2]

Post a few pictures of the problem.

[kx250.1698]

The bike is at the bike shop.  I can't add pics but piston is white.  It had a whole burned in the exhaust side of the piston, and sleeve had a crack.

[kx250.1698]

Can it be the timing that was not right!!(had new flywheel put in)That caused the engine to over heat and cracked the cylinder and caused the piston to burn?

[kx250.1698]

Aney one please!!!!need a good answer so that they can fix it!!

[Danger4u2]

If you have someone fixing it, they can see what needs to be fixed when they take it apart.  If they can't tell what it needs then you don't want them working on your bike.  You are not supplying enough information for us to diagnose the problem.  Keep in mind there are only 2 members on line right now and you are one of them.  Some times it can be 2 or three days before you get an answer.  I'm on my lunch break, that's the only reason I'm on now.
Back to work.

[hughes]

It's hard to mess up installing a flywheel but if it happens I feel your problem would have been more of a poor starting bike or back firing. The timing is adjusted by rotating the stator plate behind the flywheel. I don't think you can rotate it far enough in either direction to damage the cylinder. I suspect overheating due to lack of proper cooling but the people working on the bike should be able to inspect and diagnose the issue. Like stated before "need more information".

[kx250.1698]

It's hard to mess up installing a flywheel but if it happens I feel your problem would have been more of a poor starting bike or back firing. The timing is adjusted by rotating the stator plate behind the flywheel. I don't think you can rotate it far enough in either direction to damage the cylinder. I suspect overheating due to lack of proper cooling but the people working on the bike should be able to inspect and diagnose the issue. Like stated before "need more information".

Oke but the timing was way out before and when i got the bike the bike had still a problem of starting some times in reverse becuase of timing .so then i thought it was timing becuase some one told me if timing is way rond it can cuase bike to overheat

[hughes]

Why and how was the timing way off?? Wrong flywheel? sheared flywheel key?? wrong stator plate? cdi box failure? What fixed the timing issues you had?

[kx250.1698]

Why and how was the timing way off?? Wrong flywheel? sheared flywheel key?? wrong stator plate? cdi box failure? What fixed the timing issues you had?

Flywheel magnets was broken, they changed flywheel way out not on the marks to get it right.