KDXRIDER.NET

Ok, so here is the deal, I have a 1999 KX125 that does not run anymore. Needs more motor work than I think it's worth. After doing alot of reading, I'm interested in doing one of these hybrids with a KDX220 motor. I have read as many threads here as I can and still have a few questions. I'm semi mechanically inclined. Swapping motors, fabricating motor mounts and trimming/modifying are things I am capable of doing.

Right now my biggest question is what year or range of years KDX220 motor should I be looking for that will be the easiest fit into my KX125 frame? Also looking for any suggestions on where to find such a motor. I have scoured ebay and craigslists along with google searches. Seem to only be able to find mid 1980's motors. I don't think I would want to use a motor quite that old.

Next question is about exhaust and carburetor. Would my existing KX125 exhaust and carburetor work with a KDX220 motor? Or would I need to get matching parts for the KDX220. That wouldn't be a problem, it would just add cost to my project.

I appreciate any input you guys may have. I'm glad i stumbled on this site here. Lot's of useful information :D

As far as KDX220 engines go they are all the same. Just get the nicest one you can find that fits your budget. BTW, to get it you will probably end up buying a complete bike.

Hopefully some others will be along here to fill you in on more details.

jfmock wrote:Next question is about exhaust and carburetor. Would my existing KX125 exhaust and carburetor work with a KDX220 motor? Or would I need to get matching parts for the KDX220. That wouldn't be a problem, it would just add cost to my project.

The motor would run the best with a KDX pipe and carb (you also need the electronics from a KDX). You can probably get it to run with the 125 parts, but it won't run well. Plus you'll have spent a lot of time doing it.


As was mentioned, to get a KDX motor, you'll probably be buying a complete bike. It isn't easy finding just a motor.

ARe you opposed to looking for a 200 motor? If not, there were two on eBay recently in the $600 neighborhood. In terms of good years for motors, you should stick to 1995 and later (H series). The '89-'94 motors (E series) have a powervalve design that tends not to be very reliable. They're still reliable motors, as a broken powervalve will not strand you on the trail, but it's annoying to have to replace one or two of the valves annually. Plus, a KDX performance pipe that will fit your chassis will fit the H series motors a lot better than the E series motors, and they wont need nearly as much modification to fit.

Another difference with the E and H series motors is the headstay. The E has just a rear headstay mount, and the H has front and rear. I've seen builds where one or the other headstay isn't used on the H, and the other needed to be cut off the head to make fuel tank clearance. I think your 1999 125 has a front stay, so you probably will have to remove the rear mount from the KDX head. Not a big dean, just some careful sawzall cuts and a little die grinder action.

I do think that buying a whole bike will be an easier proposition than getting the necessary parts a la cart. It'll have the correct ignition, the carb, throttle with cable, clutch cable with lever, radiator hoses in the right configuration, correct clamp for the airbox boot-to-carb junction (you need the smaller KDX clamp to squeeze the larger KX boot down far enough to seal on the carb), the KDX is likely to already have a usable exhaust, all the right motor mount bolts, and various other useful fasteners and pipe mounts and such. Then whatever KDX chassis parts you have left over you can sell to make some money back. I think you'll probably end up spending less money just buying a used up KDX donor bike.

Good hunting!

Cool, thanks for the information. I'm not opposed to a 200, just partial to a 220. I use to have a 99 KDX220 and know how boss they are. I'm sure there is probably not a noticeable difference between 200 and 220.

Thanks for the information, I'm going to keep my eyes open for a solid running bike for cheap. I figured I needed more than just the motor

here ya go:

http://cgi.ebay.com/ebaymotors/1995-200 ... ccessories

http://cgi.ebay.com/ebaymotors/1995-200 ... ccessories

looks like all youll need is the carb/air box boot and the radiators