engine locked up


14 replies to this topic
  • erik474

Posted March 10, 2010 - 05:43 PM

#1

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

  • ForsheeMS

Posted March 10, 2010 - 05:52 PM

#2

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.

  • Santan9

Posted March 10, 2010 - 05:57 PM

#3

does it lock up only sometimes, or is it completely, permanently locked up?

  • erik474

Posted March 10, 2010 - 06:06 PM

#4

its completely locked, kickstart wont move

  • Santan9

Posted March 10, 2010 - 06:30 PM

#5

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...

  • rc4life

Posted March 10, 2010 - 06:36 PM

#6

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

  • MkUltra

Posted March 10, 2010 - 06:36 PM

#7

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

  • PAKDXYZ

Posted March 10, 2010 - 07:35 PM

#8

Thats what mine did when one of my main bearings went.

  • Santan9

Posted March 10, 2010 - 08:23 PM

#9

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.

  • brentn

Posted March 10, 2010 - 08:48 PM

#10

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

  • MXOldtimer

Posted March 10, 2010 - 09:21 PM

#11

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.

  • Santan9

Posted March 10, 2010 - 09:41 PM

#12

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


oops. my bad, I didnt see that part!

  • dirt_rider_39

Posted March 10, 2010 - 09:52 PM

#13

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

  • snooter

Posted March 10, 2010 - 10:05 PM

#14

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...

  • 2006yz125

Posted March 10, 2010 - 10:14 PM

#15

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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