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I am not too mechanical but I would like to learn to do bottom end rebuild over the winter. Good excuse to hang out in garage and drink beer. I have seen some good videos from Rocky Mountain talking about the basics of doing it.

Any suggestions or threads would be appreciated. I did search bottom end rebuild but did not find out that much. Maybe I should change my serarch terms.

Any recommendations on what parts I should order - such as gaskets, seals, bearings.

This motor is about 6 years old. I am the second owner. Comparing it to my other KDX that I got brand new - 4 years old - the motor vibrates a lot more. Really feel the buzz while standing on the footpegs. Thinking that crank bearings should be replaced.

Thanks for your time. Steve

May just be loose motor mounts!

Could be the engine bearings - Did you check for crank for play?

I think RB rebuilds cranks.

If you need a source for pounding in wedges and banging on a counterweight with a shot-filled hammer, I'm sure you could not do better...and he's right in your backyard!

Look forward to a write-up with lots of good pics!


Those pullers/splitters and such from RockyMtn. would certainly be helpful. A small press (something that a case 1/2 will fit into) is something that would certainly be of use. Beats mucking around with a vise.

Have you looked into the crankshaft jig tool to 'hold' the crank in place while you're pressing the halves back together? I'd sure want one'a those.

There is a crank install tool that eliminates the need for a press to get the assembled crank back into the cases and the case halves back together. Just make sure all the tranny shafts/shift drum are in the right places or you will probably crack the case when you put the squeezation to it.

Good ideas guys. Yes, although I have never talked to the mythical Ron Black before I understand he is very close to my location. About 20 miles away. So he would be a great resource and his prices are always very reasonable.

Best to send him an email, I'd think. I don't know if I recall correctly that he rebuilds cranks..but I think he does.

Probably not a lot of reason to assume that the crank needs to be split..didn't mean to imply that it would be a GP approach if you're inside for a bearing replacement. It was an 'in case (ha ha) you need to....' comment.

That crank installer sure beats pressing the crank in. The crankshaft 'jig' tool (not what it's called..the name of it escapes me) I mentioned isn't needed if the crank is pulled into place, but only if it's pressed into place.

Ron was willing to replace the big end bearing on the YZ. I ended up just getting a complete HOT Rod Crank only because it was faster and I needed the bike together for a race.

and this is the one I have..

http://www.rockymountainatvmc.com/produ ... lyId=17166

Yeah, can split the case, but leave crank work to pro's. That's a cool tool! Colorado, did you stroke the 125 while you were at it?

Nope, I wanted to, but it already cost me a bundle since the kid blew up everything. I had to put in a new crank, Piston kit, water pump seals and bearings, shift stop gizmo, all the tranny bearings needed to be replaced, plus a power valve which cost $168 with a discount .

I've put a LOT of hours on KDX's and never had a lower rod bearing fail, so I never replaced one, even through two complete lower end rebuilds on the same bike. I always replaced the crank bearings and seals. I guess what I'm saying is the job is a lot simpler if you don't split the crankshaft (unnecessarily).