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PAKDXYZ

KX 250 Siezed Up

30 posts in this topic

I have a 97 KX 250 and while I was riding today the motor siezed up. About an hour before it completely siezed. I was kickstarting it after a break and it was really hard to kick over then all of a sudden it was fine a started and ran great. Then I stalled it and it the back tire locked up and the kickstarter wont move either. I pulled the head when I got home and the piston is almost at the bottom of the stroke, there is no visable damage to the piston or cylinder, I have not taken the cylinder off yet. I am just wondering what my possible scenerios are here. Best case I am guessing I will need a top end, I was wondering if there was anything in the bottom end that could cause this to happen. I think I am going to open up the cases anyhow since I dont know when the bottom end was last serviced. I was just trying to get an idea from anyone who might have experience with this. Thanks for your help.

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If the problem is in the crank, you might need a new top and bottom end.

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I know I will def. need the top. I might just do the bottom too regardless. I picked the bike up for next to nothing in a trade but I don't know the service history of the engine so it is probably something that should be done anyway with the age of the bike. What in the bottom end could have caused a seizure, a toasted bearing??

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I know I will def. need the top. I might just do the bottom too regardless. I picked the bike up for next to nothing in a trade but I don't know the service history of the engine so it is probably something that should be done anyway with the age of the bike. What in the bottom end could have caused a seizure, a toasted bearing??

exactly the, crank bearings or rod bearing, ussually its the rod. time to split the cases and do a top and bottom

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If it was the piston to seize you definately would have noticed some sort of nastyness on the cylinder walls.

Sounds like you need to do the crank & bearings.

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Once I get it apart and verify that it was the bottom end, if the piston and cylinder check out OK is it necessary to do the top end as well? I am not opposed to spending the money on it, just wondering if it has to be done.

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Once I get it apart and verify that it was the bottom end, if the piston and cylinder check out OK is it necessary to do the top end as well? I am not opposed to spending the money on it, just wondering if it has to be done.
I know I will def. need the top. I might just do the bottom too regardless. I picked the bike up for next to nothing in a trade but I don't know the service history of the engine so it is probably something that should be done anyway with the age of the bike. What in the bottom end could have caused a seizure, a toasted bearing??

A Wise Man would do it. :bonk: Have you ever seen a piston skirt in your crankcase? ...or pushed your bike back 3 miles from the woods?

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yea I shouldn't have asked that question, I already knew the answer. :bonk:

Here is my next question, I just pulled the cylinder(looks great). Turns out there is a hot rods crank kit in it, which makes me feel a little better knowing that maintenance was done before. The rod has a bit of side to side play but no up and down and it moves back and forth smooth so I believe it is one of the crank main bearings that is toasted. I had planned on just ordering a whole new crank kit from hot rods or wiesco, but now, assuming there is no damage to the crank itself, and it is in spec, would i be ok just doing all the bearings on the bottom?

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I had a Suzuki 90 and the same thing happened after a top end rebuild with new piston. I couldn't figure out what the problem was. I gave up on it. I let my friends ride the bike and ride it they did. They literally rode the hell out of it. Then the bike ran fine.

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Well, you could go cheap and just replace the crank bearings but let's think about this:

Most people replace crank bearings when they replace rods, so they are at least as old as the rod bearing. The crank bearings get mainly rotary motion, and they are beefier, so not loaded as much as the rod, yet they failed first. So what caused them to fail and how far behind is the rod?

Roller bearings are tricky things. They rarely develop any clearance, so when they do, you know they are fried for sure. Usually the "noisy roll test" will tell the story. A good bearing will roll quietly, but then, pretty hard to apply this test to a rod big end.

For all the work to get the engine out of the frame and split apart, there would never be a better time to freshen everything up in there. I would save money on a piston before I saved it on a questionable rod.

There is never enough time or money to do it right, but there is always enough to do it over.

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Is there any dark coloring around the rod bearing? Like sbest said, if the crank bearings failed I'm sure the rod isn't too far behind.

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I would definitely be replacing the rod bearing, my question is would there be any reason I couldn't re use the actual crank and rod. After getting all my prices on bearings, seals, and labor to rebuild the crank, it is really only a couple bucks more to get the whole assembly from wiesco. I found it at oemcycle.com for 159, and that includes all the bearings and seals, so I think I will go that route and I will feel better as well.

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Yes, the prices have come down on the crank kits.

There is no removable race on the rod. When you rebuild a crank you replace the rod. Think of the rod as a bearing race. Bad bearing=bad rod.

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Yes, the prices have come down on the crank kits.

There is no removable race on the rod. When you rebuild a crank you replace the rod. Think of the rod as a bearing race. Bad bearing=bad rod.

I did not realize this. Ok so a whole new crank kit it is, Now I just have to decide if I want to go with the Wiesco kit or the HOT RODS kit, I have read good and bad reviews about both.

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I used a Wiseco in my 2000. Only problem I had was the groove for the key was slightly narrower than the key itself. I had to use a jewelers file on the key to get it to fit. Not a big deal, but that's what happens with aftermarket parts.

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I used a Wiseco in my 2000. Only problem I had was the groove for the key was slightly narrower than the key itself. I had to use a jewelers file on the key to get it to fit. Not a big deal, but that's what happens with aftermarket parts.

Other than that one issue, were you satisfied with the quality of it? Also were the bearings and gaskets that come with it of good quality as well?

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Besides the key, it was fine. The gaskets, bearings and seals were perfect. I ran it for a year after with no issue, then sold it.

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I have been hearing alot of bad things about Wiseco cranks lately. I hear they are Chinese now. :bonk:

I don't know about that, but more than you know is Chinese anymore. :bonk:

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