Rebuilding seized 07 CRF 250r

Alright so a few months ago my dirtbike locked up for the second time i have drained all fluids. dont remember if there was metal flaking in oil filter or not it was a while ago that i checked. but i just drained the tranny fluid and a metal chunk came out about a 1/16" big and fluid was grey. i have just got done pulling the motor out of the bike and am waiting for my flywheel puller to come in before i get any deeper into the engine. if anyone has any suggestions of what it might be post it. and anything to watch out for when splitting the cases which i will be doing anyways cause i dont like the fact that there is metal peices in the engine that will mess up other stuff.









Buy the factory service manual and read it. Relatively straight forward to split the cases. Inspect everything very closely and clean everything we'll also.

Was the chunk that came out steel or aluminum?

aluminum and ive got the service manual and 4 hours worth of videos that show every thing from taking the seat off to putting it back on and the guy on the video had a siezed motor too but not as bad. i just got done taking off the head and valves were not exactly in the right spot and im pretty sure the piston is broke in half because the top half i can spin but it is stuck in the cylinder so does anyone have any tips to get it out of the cylinder?




Not good, you dropped a valve into the engine, how many times have you shimmed them?

new head

new piston

maybe a cylinder

I would replace the crank since it had a big impact

It's going to cost $$$

When was the last time you changed a piston? That piston is roached!

Thanks for replying man the guy who rebuilt it after it locked up the first time I think he said that the water impeller was what cause it but who knows cause it didn't have many hours at all on it when it did this. I paid him like 700 to do it and he never charges labor and has rebuilt me an my cousins top ends on our four strokes with no problem but he has done something wrong twice on my bottom end. He had to of replaced valves, crank, piston and rings, bearings, who all knows but this time I'm doing it myself so I'm the only one to blame if something goes wrong. Oh and i know he shimmed the valves if he did all that work and I've never had a problem from him when he shims our valves

Oh it's probably been 7-8 hours since all that was done:/

That piston looks like it has way more than 8 hours on it. I would do the crank and all the bearings in the bottom end in addition to piston, cam chain, tensioner, valve job and new valves

For $700 the dude should have replaced at least the piston esspessially on a locked up motor but if not the damage is already so I'll just see how much damage is done and replace it all if I have too

Just wondering if I could take the side cover off and stick a ratchet on the flywheel nut and try to break the piston loose that way or would I even get to the flywheel but by taking the cover off?

just hit it with a hammer, you can't mess it up any worse

Yeah but if I can pull the piston straight out I might luck up an not have to buy another cylinder

Easiest way is to stick the bike in 5th gear and turn the wheel backwards, you get lots of leverage that way, but you pulled the motor out.


You could use a wrench but tapping the top of the piston with a hammer is more effective.

Yeah but my bike won't go any higher than first gear anyways. I'm tellin ya man dude messed my bike up in all kinds of ways

So the next step was to get the cylinder off which I had to get the piston out of. Finally got the piston out and found out the rod had broke which messed up the cylinder which made it a pain in the ass to get it out of the cases. So I got it out and found out that the cases were both broke when the rod broke so what's y'all's suggestions for what I do nextImageUploadedByThumper Talk1382749982.595013.jpgImageUploadedByThumper Talk1382749995.515188.jpg

Oh and what do you know. It a wiseco crank

Dude that sucks...

You're gonna have at least 2 grand into that IF you do all the work yourself...

And the last guy "not charging for labor" was pretty fishy smelling IMHO.

And, someone please correct me if I am wrong, but the last picture shows a screw in and bolt on oil jet????n/m it's the screw in restrictor

Edited by dirtydrew

Nah the bolt was just where the case broke around it. And the guy that we had do it has been rebuilding our bikes since me and my cousin started riding. He's my cousins real good friend. I just don't think that he new wiseco cranks were shitty.

Nah the bolt was just where the case broke around it. And the guy that we had do it has been rebuilding our bikes since me and my cousin started riding. He's my cousins real good friend. I just don't think that he new wiseco cranks were shitty.

It likely had metal left in it from the previous seizure that contributed to the short life of the big end bearing on the new wiseco crank

Yeah but after each of the first three rides I changed the engine oils and tranny fluid but I'm sure extra metal did have something to do with it even though metal stopped showing up after the first oil changed

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