Well it is starting to look like a bike.....

This is a KX125/KDX200/KX250 project.

This is the first mock up to check for clearance and any other unanticipated issues.


I can lower the motor just a tad more by grinding the cases. Pretty clear where the bottom mount neds to go.


Pipe fits suprisingly good. Aftermarket pipe can be bent pretty easily to fine tune. I got this from ebay for $12. It is basicly just a template. I ned to fab up some mounts for the pipe.


On a KX, what are these 2 nits for. I suspect they are exhaust hangars. I need to cut the top one off or dent the pipe tpo really get it snug. Here arae two shots from top ad bottom.



That's it for now. Any help with the 2 questions would be appreciated. Next time the mounts will be in and the frame will be stripped and repainted. Hopfully the motor willl be fully rebuilt and cleaned as well.

Anybody know what those frame nuts are for?

went into the garage to look for ya i have a 2000 kx125 n it only has 1 of those frame nuts and its an exhaust mount.

Ahh thanks brotha! The top one if getting cut off then.

what parts of which bikes are you using?

I'll put together a list when done. It ranges from 97 to 2002.

Most parts are 1999-2001 and a combo of KX250 and KX125. Suspension for example is 1999 KX250 and the swingarm is 2001 KX125 and the linkage is 2002 KX125. Apparently there was some ratio changes in 2002 for the linkage which improved suspension near bottoming.

please keep us updated on this thing, I didnt know people had the balls to do this shit! cant wait for a ride report also to see how it all works, yeeeehaaawww!!!!

You don't show any sprocket side pictures. The height of the motor is dictated by the sprocket center and the swingarm pivot bolt center, they must be plumb, if not your going to have chain tension issues. You can't move the motor up and down as a convienence. It can only be mounted to achieve plumb.

Hmmm, I'll post up a pic of that. So the swing arm and sprocket centers bust be level? Is this with both wheels on the ground or with the frame on a stand?

Looks awesome so far!

It doesn't matter, whether the wheels are on or not, just so the two center line up. As an example, if the sprocket center is higher than the swingarm, as the wheel moves up the chain will get looser. If you look at any bike you will note that the two are on the same plane.

No I don't mean with the wheels just on. I mean with the bike standing on it's two wheels or with the bike on a stand? For example, I can raise the forks and lower the shock and get a chopper ride and the sprocket will be physically higher thant the swing arm bolt. See what I mean.

I am not arguing I am trying to understand what plane means.

Watch out for the different parts, M1/M2. I dont know about that model year, but on my bike, the M2 pipe will not fit my M1 bike.

The way I understand it when the swingarm is half way in its travel the front sprocket the swingarm bolt and the rear axle should make a straight line. Not sure how correct that is but that is what I think it is. Ed

Ok that makes more sense.

The swingarm pivot bolt is fixed, so you can't change that. The motor could be moved up or down assuming you have the swingarm bolt in and no motor mounts. ideally the sprocket center and the swinarm center are equal with the bike reasonably level. Maybe the easiest thing to do is look at a stock bike, note how the sprocket and swingarm pivot are aligned and perhaps it will make more sense. I've done four different motor swaps and can tell you that is the most critical point of the installation.

I did compare my motor to a sock KDX. The swingarm pin/rear motor mount are fixed. that can not be changed. the bottom of the motor has the exact same clearance at the exact same spot as the KDX does. Once I get wheels on I'll check it out.

It is hard to tell on a bike chasis stool as the KX125 has a pretty good bottom tube slope.


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