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KX250 2000 Bottom End Problems (with pictures)

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Hello - I think my KX250 doesn't like me any more smile.gif
I've had the bike for 4 years and last year had complete bottom end rebuild done. The bike ran fine for about 30+ hours (I am intermediate rider and most riding was done on the trails).

The "problem":
While riding the bike suddenly lost all power and just died on me. It didn't lock up but wouldn't start after a few kicks. I opened it up, replaced top end and it fired right up.

The "fix":
During the "break in" I noticed knocking from the engine and about 30 seconds later the bike died. I discovered that the new piston skirt has exploded. After 2nd look at the crank it looks like the crank or the bearing has failed. I am not sure. irked.gif 
Take a look at the crank pictures. Is the white material melting? Why? Should I rebuild the crank or replace bottom end completely? 
Why the heck is this happening?


Thanks!

 

 

Crank1.png

File_000.jpeg

File_002.jpeg

Edited by IndiGIXXER

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Sure looks like a Wiseco crank am I right?  Another one bites the dust.  I really don't know why people still buy these things.  Lucky for you it didn't blow chunks. 

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Sure looks like a Wiseco crank am I right?  Another one bites the dust.  I really don't know why people still buy these things.  Lucky for you it didn't blow chunks. 

 

It wasn't Wiseco.... I don't remember the brand.

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Lower rod bearing went, when that happens the piston skirt contacts the crank halves.  The white stuff is crank stuffer.

 

You are probably 100% correct.  I could see the (remaining) piston skirt touching the crank halves when I opened it.  

 

Why did lower crank bearing fail so soon? Anything I could have done to identify the problem before it happened? 

Edited by IndiGIXXER

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Did you prelube the bearings when you assembled the bottom end?  I pour oil on all of them and give them a few spins.  After 30 hours, could be anything from bad bearing/materials to lean condition.  Was the old piston oily when you removed it?  Any scoring?

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Did you prelube the bearings when you assembled the bottom end?  I pour oil on all of them and give them a few spins.  After 30 hours, could be anything from bad bearing/materials to lean condition.  Was the old piston oily when you removed it?  Any scoring?

 

Yes, berings were lubed. The old piston had some scoring but see for yourself....  I'll add the piston picture to the first post.

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It wasn't Wiseco.... I don't remember the brand.

 

I was pretty sure when I saw the "W" on the rod and the melted stuffers.  What does it say on the rod?

 

Sure looks like one of these:

s-l1600.jpg

Edited by turbo dan
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I was pretty sure when I saw the "W" on the rod and the melted stuffers.  What does it say on the rod?

 

Sure looks like one of these:

s-l1600.jpg

 

 

Yup, I see the "W" on the rod as well.  I can't think of any other manufacturers that start with "W".

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Could it be a wossner?  I don't see the "I" after the W in OP's pics

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If that was a Wossner rod kit I imagine this guy wouldn't be back into his motor at 30 hours.  The EZ-melt stuffers are a feature I've only seen on Wiseco cranks too.  Judging by the slight bluing the crank didn't even get that hot.  He didn't run it that long once it began to fail which probably saved the cases and cylinder.

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I was pretty sure when I saw the "W" on the rod and the melted stuffers.  What does it say on the rod?

 

Sure looks like one of these:

 

 

 

If its a Wiseco, thats your problem, I guess we got an update as to whether they fixed their crank issue.... or not.

Not sure why the OP is in denial.

 

 

Could it be a wossner?  I don't see the "I" after the W in OP's pics

 

 

DAMN!   :facepalm:  It is Wieseco.  I don't know why I thought it wasn't... anyhow now we re-confirmed that Wieseco cranks are still crap!

 

 

So what other should I get (other than OEM)???

Edited by IndiGIXXER

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Hot Rods might work.  I used one in my 03 125 many years ago and that was a good crank.  They have had some issues though.  I put a factory Kawasaki crank in last time I did the bottom end in my 250 and I expect to never have to service it again.  Hell, the one it replaced was still good at what I can only estimate was 400-500 hours.

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At least the cases are still intact and the motor did not completely disintegrate. There's still hope for this bike. Install an OEM a pro-x rod pressed on a oem crank or a hot rods crank.

If you choose the Pro X route then get in contact with Ken O'Connor racing. He presses them on and trues them very straight.

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The problem is you or someone else tossed the original crank that COULD HAVE been rebuilt by Mr. Crankshaft, et al.  No sense rebuilding a p.o.s. Wiseco, you never know what's gonna fail.  

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