Is it time to replace my crank?

[upnorthbacon]

2000 kx250 just purchased. How do I check the crank bearings need replacing? Mostly curious about the bottom bearings? I took the pipe off and can move the crank slightly back and forth through the case? Is that normal? I'm assuming I have to take the jug off and measure something to know for sure? What special tools will I need if I buy the hot rod kit which comes with the crank?

 

[WillyM]

I have found with my KX is when in doubt replace it.
The bottom end berrings are pressed onto the crank ,and you could just replace them .
The rod bottom berring should have no up and down play that you can feel.

 

[KaTooMer]

A little side-to-side play is O.K., like Willy said, it's the up-and-down play you don't want. When that happens, it's often the big-end bearing (on bottom of the rod) that needs replaced. If that's the case, the crank halves would need to be separated. I don't know too many people who have the tools to do this themselves. The cost of having it done - with a new rod - is probably about the same as buying the complete rod/crankshaft from Wiseco (have seen these for $180-190 on eBaay). Installing the complete kit is more doable for the mechanically inclined.

 

[Camstyn]

When my bottom end started to go on my '00 KX250 it began making a whirring noise, most noticeably on deceleration.

 

[noosa_nick]

Remove your engines left hand side cover and check the rotor for any movement. If you find any your crank bearings need replacing.

 

[upnorthbacon]

Thanks for the replies.