Jump to content

KX100 Bottom End Question


Recommended Posts

Hey All, I'd like some opinions on how much to replace. Here's the deal:

'05 KX100, pretty low hours, all original motor. Riding in March it locked up while running but would fire right up again, but now making a wierd rattling sort of noise while it ran, so we didn't run it any more fearing more damage. Top end was in great shape, but I cracked the case today and found what I expected - very bad left side main bearing. It was intact, but really dry and gray, bumpy running, and had gotten hot enoughto start melting an d deforming the seal. No evidence that the race spun in the case. Rod big end feels good, piston & cylinder show very little wear and measure well within original spec. I may have caused this failure by running too little oil - was running amsoil at 44:1, have since found out that most are running 32:1 and say this motor needs an extra oily mix. ­čĹŹ So here's where I'd like opinions:

1) Should I just replace the main bearings and seals, throw the original crank and rod back in, or should I replace the whole crank assembly for good measure? I'd rather not crack it again later, but now that I have the tools and experience it would be much easier.

2) If I go with the whole new crank assembly, can I / should I use the '06 and newer crank? The '05 and prior uses a snap ring to secure the primary drive gear and the '06 and later uses a nut. Does the '06+ have any other improvements such as better bearing life?

Thanks in advance for the help!

Jack

Link to comment
Share on other sites

1) Should I just replace the main bearings and seals, throw the original crank and rod back in, or should I replace the whole crank assembly for good measure? I'd rather not crack it again later, but now that I have the tools and experience it would be much easier.

2) If I go with the whole new crank assembly, can I / should I use the '06 and newer crank? The '05 and prior uses a snap ring to secure the primary drive gear and the '06 and later uses a nut. Does the '06+ have any other improvements such as better bearing life?

Thanks in advance for the help!

Jack

1) you answered you own question

2) You can't without replacing stator, flywheel, primary gear.

Link to comment
Share on other sites

Buy the Wiseco kit PK119. It comes with the crank, crank bearings, and all the gaskets and seals you will need to get it back together. Retail is only $165 and if you shop around you can probably get it cheaper. The '95 and up models all use the same crank bearings so no need to change to the newer crank.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

├Ś
├Ś
  • Create New...