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erik474

engine locked up

22 posts in this topic

what would cause the engine and kick start to completely lock up? im just wondering what all i might have to get myself to do to fix it, top end? bike is a 2002 cr250

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Could be the crank or the top end. Really no way to know without tearing into it. Once you get the top end off you should be able to tell.

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its completely locked, kickstart wont move

yeah thats not good at all.. I would start taking the engine apart. it could be your piston/cylinder thats seized, or it could be the crank/crank bearing thats seized. either way this doesnt sound good at all and you better be prepared to spend 1000$+ in the next few weeks...

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could be something as simple as a shot head gasket causing your engine to hydro lock from the coolent pouring into the cylinder... but more than likely its a siezed piston or crank bearing

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you could prlly rebuild the crank and throw a new piston in there for about 400$ if that, thats if you dont have to re-plate the cylinder. re-plate is like another 200$, plus add in crank bearings and a gasket set

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you could prlly rebuild the crank and throw a new piston in there for about 400$ if that, thats if you dont have to re-plate the cylinder. re-plate is like another 200$, plus add in crank bearings and a gasket set

yeah, and thats if he does all the labor himself.. from what ive heard, changing a 4 stroke crank isnt easy and requires a lot of work. id imagine youre looking at 5-8 hours if you bring it to a stealership.

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Start by taking the whole clutch side cover off, take a look at your basket and primary drive gear. Remove the primary drive gear and see if your basket spins freely when in neutral. Check the kickstart and idler gear etc etc. Rule out the transmission/clutch area.

It's good to rule things out one thing at a time, the easiest thing at a time. Clutch side cover is easy to take off compared to removing the top end.

If that's no good then start with the top end, remove the head, then try and remove the jug. If the jug comes off easy then it's def a crank bearing problem for sure, if it does not then the piston is siezed in the cylinder.

Good luck

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yeah, and thats if he does all the labor himself.. from what ive heard, changing a 4 stroke crank isnt easy and requires a lot of work. id imagine youre looking at 5-8 hours if you bring it to a stealership.

He said

bike is a 2002 "cr250"
plus on a thumper it isn't hard to pull the crank.

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He said plus on a thumper it isn't hard to pull the crank.

oops. my bad, I didnt see that part!

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pull the spark plug....and see what happens.....on a stand put it in 3rd and turn the rear wheel and see if it turns over...if it does then its the kick starter/clutch...if not then tranny and piston..

good luck

post the results and we will help from there

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crank bearing exploded..hopefully it did not suck thrust washer up into the jug...dont ask me how i know..this is the biggest cause of all vintage dirt bike failures...for you vintage guys the crank bearing rusts from years of sitting and upon starting our classic vintage-make all the neighbors drool bike we are treated with disrespect by the bike and that damn SOB thrust washers ends up in the jug..(well on my old iron it does)...could be seized piston as well..everything above is correct..aka..engine rebuild...

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sounds like you have a seized topend... this will be a pretty easy fix... new topend... possibly just a new piston unless the cylinder has takin damage too...

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I have a 05 CRF450R bought it with a locked up motor. It moves freely in neutral and what not, but the kickstarter won't budge. Any idea?

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I have a 05 CRF450R bought it with a locked up motor. It moves freely in neutral and what not, but the kickstarter won't budge. Any idea?

Umm yeah the motors locked up, but you knew that right?  It moves freely in neutral cause the trans is fine.  Time to tear it down and find out what went wrong. 

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Umm yeah the motors locked up, but you knew that right?  It moves freely in neutral cause the trans is fine.  Time to tear it down and find out what went wrong.

based on your opinion, the piston sounds as it moves when I push it, could it be the crankshaft and or kickstart gears?

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Ya know this is the 2 stroke section, right?

Edited by KcDavis

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I'm guessing if you have recently put a top end in it, it's not broken in right. It could also have something to do with the rod or rod bearing. Something of that sort. I'm only 16 what do I know comment back telling of my accuracy.

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