How did I shatter my piston? I need help!

[jharmon]

I need help. Here's the scenario. I own a 1993 KX 250 and I went riding on a closed track this weekend. I would take a couple laps (the track is about a mile long with various jumps) then take a break. I did this for about 3 hours, and my bike never got really hot, but on my last lap I hit a couple of small jumps, then my piston just shattered. I have no clue how this could have happened. I have been running my gas 42:1 for the last year.

The piston was about 1 year old, and I did do a lot of riding on it. Is it possible the piston just got weak and broke? Or could there be something else.

I notice the rod has a little bit of sideward movement, as if the bearings are shot, but a friend told me that the rod is supposed to have a little side to side motion, so the rod doesn't break.

I also noticed that there are some burn marks on the piston. There is also some pieces of metal in the lower half of the engine, is it possible to flood the pieces out with oil or some kind of solvent, or what should I do? If anyone can give me some advice as to why this happened, I would greatly appreciate it. I don't need this happening again. Thanks in Advance! :confused:

 

[RM_guy]

Jeff,
Is it possible that the abundant carbon build up on the top of the piston may have broken loose and caused the piston to break? (don't forget I have inside information) ;)

Was the cylinder bore worn past spec? If so the excessive piston slap can cause piston failure.

Was it a OEM piston? Stock, cast pistons will break if run too long. How many hours did you have on the piston?

I know people that have tried to flush out the piston pieces from the crank but the only way to be sure is to split the cases. If any pieces stays in there it can become dislodged and cause havoc later on.

BTW, replace your rear wheel bearings too :eek:

 

[jharmon]

Ihave no idea if the break was from abundant carbon. It could be, since there was a lot. I don't know what kind of piston it is, it must be stock.

I really don't want to spend a lot of money getting the case split, but it sounds like I might have to.

Thanks for the tip on the wheel bearing. Obviously you've been talking to Rimbey. Tell him to stay off the doubles, he can't handle them yet!

Thanks Dave.

 

[RM_guy]

Originally posted by jharmon
...Obviously you've been talking to Rimbey. Tell him to stay off the doubles, he can't handle them yet!...

You wouldn't believe the stuff he tells me.:eek: I can't wait to ride with you to see how true it is. He's quite the story teller.

He does need to stay off the doubles though. Just because he jumped off the porch doesn't mean he can jump the doubles. :confused:

 

[jharmon]

I think Rimbey thought he was Carmichael for a second. Don't let him BS you too much. We're not that good. I just like to have fun, and I usually go at my own pace.

I have a couple of friends that are fearless and always trying to get me to do more than I'm ready to. I don't fall to peer pressure too easily.

Rimbey does. At least he's off the porch and running with the big dogs now.

 

[mackay]

SHattered Piston

hey there jharmon ;

so your piston was 1 yr old with quite a bit of time on it??
IMO it sounds like that piston was probably slappin around in the cylinder pretty good as in worn past spec. If it shattered then your gonna have to get any bits of metal out of the crank cases so splitting the cases would probably save you a whole lot of money down the road. Just think of the cost if you button it back upo without splitting the cases and end up chewing up crank and big end bearings $$$$$.
Just my thoughts on the problem since you probably would rather be doing this :aj: than this :whiner:
hope your back out there soon

 

[jharmon]

Thanks a lot Mackay. Actaully I'm going to the local Kawasaki dealer tonight after work to get a price on splitting the case. Thanks for the advice. It sounds like I might have a little down time the next week or two, but I'd rather have it now, then in the middle of summer.

 

[truespode]

Compare the dealers pricing with www.2fastracing.com

They charge a flat rate and not by the hour.

Good luck.
Ivan

 

[jharmon]

Truespode, you're a good man. I'll check it out right now.

Thank you.

 

[truespode]

If the url doesn't work try giving Eric Gorr a call and ask him for Jim's number.

Sometimes I can't get to the 2fast site.

Ivan

 

[jharmon]

I'm having problems getting to the site already, I'll try later. If that doesn't work then I'll call Eric Gorr.

Thanks again.

 

[truespode]

I've had trouble getting to that site too. I'd call Eric.

Good luck.

Ivan

 

[truespode]

Oh... if that doesn't work e-mail mxtuner@mindspring.com and see what he may be able to do for you. He does bike stuff on the side. He works on BMW's during the day.

Ivan

 

[MikeKX250]

2Fast racing, Call Jim Neupert 1 608 244 2801. Nobody does better work, cheaper and stands behind it like Jim. He is the Eric Gorr of bottom ends. Unless you can`t wait for Jim to do it don`t even think about using anybody else. If you send Eric a complete motor he sends the bottom end over to Jim at 2fast.