Piston exploded in cr250

So i am rebuilding my buddy's 2001 cr250. When i took the cylinder off i saw what happened. The piston was destroyed. What do you think was the cause? 

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There is no question what happened.. He ran the piston beyond it's service limits and the skirt let go. This happened to me end of March this year as well, also on my 2001 CR250.

 

It cost me over $700 in parts, with me doing all the labor, to fix it. A piece of skirt went into the crankcase and got wedged between the crank stuffers & the case halves and blew a chunk out of both case halves. I ended up having to get cylinder re-sleeved, new piston, new rings, rebuilt crank, all new bottom end bearings.

 

Ken O'Connor racing is who I used and I would HIGHLY recommend him. His work is awesome.

Looks like some serious detonation was happening too.

Edited by CamP

Looks like some serious detonation was happening too.

What Cam says!

So i am rebuilding my buddy's 2001 cr250. When i took the cylinder off i saw what happened. The piston was destroyed. What do you think was the cause?

Very nice

There is no question what happened.. He ran the piston beyond it's service limits and the skirt let go. This happened to me end of March this year as well, also on my 2001 CR250.

It cost me over $700 in parts, with me doing all the labor, to fix it. A piece of skirt went into the crankcase and got wedged between the crank stuffers & the case halves and blew a chunk out of both case halves. I ended up having to get cylinder re-sleeved, new piston, new rings, rebuilt crank, all new bottom end bearings.

Ken O'Connor racing is who I used and I would HIGHLY recommend him. His work is awesome.

I thoughtbu said you did all the work. I'm confused.

The 92-01 motor will break the skirt if you run it past its time but like Cam said that motor had some serious detonation going on. Air leak, low octane fuel are some of the possibilities.

dirty, I did all the LABOR..  I live in Houston & shipped my parts off to KOC. Ken O'Connor did the machine work, milling the head, re-plating the cylinder, rebuilt the crank-you know those things that we home-mechanics can't do at home..

 

I separated the case halves, sent them out to be welded by a local aluminum welding specialty shop, pulled & replaced all bearings, seals, gaskets, pressed all the bearings, put all the fresh parts back together.

Looks like some serious detonation was happening too.

Looks like some serious detonation was happening too.

Agree, That is a melt down condition. Lean jetting, Air Leak, Lack of octane in fuel. Some or all of the above.

Looks like some serious detonation was happening too.

As you said and look at the silicone reed gaskets , probably lean too. 

There is no question what happened.. He ran the piston beyond it's service limits and the skirt let go. This happened to me end of March this year as well, also on my 2001 CR250.

 

It cost me over $700 in parts, with me doing all the labor, to fix it. A piece of skirt went into the crankcase and got wedged between the crank stuffers & the case halves and blew a chunk out of both case halves. I ended up having to get cylinder re-sleeved, new piston, new rings, rebuilt crank, all new bottom end bearings.

 

Ken O'Connor racing is who I used and I would HIGHLY recommend him. His work is awesome.

Only shop that will touch my machine work and he will answer the phone  :thumbsup:

Looks like this was caused by severe lack of maintenance and proper care.

Hello again, so i have some shots of the cylinder and want to know if it is in good enough shape to hone and rebuild. Obviously i am no expert in this area so i will lean on you kind folks.

 

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That cylinder needs to be replated. 

Hello again, so i have some shots of the cylinder and want to know if it is in good enough shape to hone and rebuild. Obviously i am no expert in this area so i will lean on you kind folks.

 

 

 

 

 

If there are no grooves that catch a fingernail and no cylinder plating missing, you can reuse the cylinder after a little glaze breaker or scotchbrite work.

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