KDX / KX 125 Hybrid

[sintax]

So whos made one?

I'd really like to pick up a 2005+ KX125 roller and tossing in one of the spare KDX engines I have (1991)

Figured it would complement my KX500/250 hybrid well...

[don46]

so did you do it? I'm kinda thinking the same thing, built the AF framed 250 2t for the wife but I think its to much bike for her, so now I'm thinking about doing the hybrid and since I have an 02 125 frame thats what I'd use.

[Goat]

I would imagine it would be easier than doing a 500 into a 250 frame. The kdx is pretty close to the same size as the 125 with a slightly bigger jug on it. It wouldn't supprise me any if it just bolted in actually. I'm interested in doing this now

[don46]

I'm going to do it, I picked up two KDX 200's, an 89 and 91, both are complete and run. I'm going to make sure I have the parts I need and part out the rest of the bikes. I've got a bike on the Jig right now and then I'm having rotator cuff surgery the 21st of Mar so after that I'm going to hit it.

[DoldGuy]

Check this, He has done one already.

http://www.kxriders.com/forums/index.php/topic,7794.msg59996.html#msg59996

[Friar-Tuck]

 and says there is help avail. here

I got all my information to do the build on KDXrider.net  (i hope I can say that here?)  They have a KDX-MX Hybrid forum.  GREAT info.

 Tuck\o/

[The Flyin Hawaiian]

This is a pretty popular conversion, theres guys on TT forum doing it as well as on KDXRider. Ive been thinking of doing one after the 500 is done, whenever that is.

[Goat]

I'm going to do it, I picked up two KDX 200's, an 89 and 91, both are complete and run. I'm going to make sure I have the parts I need and part out the rest of the bikes. I've got a bike on the Jig right now and then I'm having rotator cuff surgery the 21st of Mar so after that I'm going to hit it.

Awesome! Must get lots of pics and start a build thread. Hope your surgery goes well. Keep us posted.

[don46]

gathering up the parts, I'm using a 02 kx 125, primarily because there are a boatload of parts out there. It is my intention to assume the parts are junk and will need to be rebuilt so I re do the forks, shock all the linkeage new seat cover, rebuild the motor and powdercoat the frame and swingarm.

[sintax]

Don: I have not made any progress on this yet. I'd still like to do it, but just have a lot of projects up in the air currently. I have a 1991 KDX as a donor, but I just need to find the late model KX125. I kinda want to avoid the 1999-2002 era KX's due to the lack of parts in the near future.

Then again, maybe i'll just say screw it and go buy a 2011 GasGas 300 since thats really what i want =)

[PowerFiend]

If someone needs a large tank (Black Clarke) for a 03+ KX125 KDX hybrid I have one. It is already molded around the KDX head water inlet/bleed port, but may need additional forming around the rear head stay depending on how you do it. The frame requires all the mounts but swingarm to be moved, so that is a bit harder, but pipe and rads are easier than a 500 conversion.

I originally started doing one of these 97 KDX220 motor into a 03 KX125, but in the end traded the KDX for a KX500. So I have a few parts that won't work with my now KX500 motor into a 03 KX perimeter chassis. 

[don46]

I started my conversion, it is basically mocked up only thing lacking is the pipe. I have a couple of 125 pipes that could work, I also have a buddy that has a newer KDX with the perimeter frame, I think I will try his to see what is easiest

[Goat]

Needs pics? lol

[doctord]

I just finished a hybrid using a 2002 KX125 chassis and KDX 220 engine. Pretty easy job overall.
I chose a 2002 chassis because I'm in California and it is the last year of the green sticker and it has the 48mm forks.

Click the picture to see some pics.



I already posted this on KDXRIDER, but here are some things I found along the way:
1. The new Bill's pipe I bought had too short of headpipe to work. I was able to make some slight bends to an FMF desert pipe to make it clear the frame, radiator and meet up with the silencer. I used some fat bars for my bending leverage tool. I swapped the pipe mounting brackets top & bottom and made an extension bracket for the top mount.
2. I bought a Turbinecore SST silencer for a KX250 and made a couple of brackets and a bend to the inlet pipe to move it forward enough and meet the chamber pipe.
3. I did not cut off the existing motor mounts. I removed the inside half of the lower mount on each side and elongated the mount bolt hole with a dremel to line up with the engine bolt hole. I then made a plate to reinforce it and riveted it in place on the outside of the existing mount. Similarly I made a plate for the top mount and bolted and riveted it to the existing mount.
4. I used a petcock from an '87 KDX. It has a reserve and the outlet pivots.
5. I used the front fender, number plate and triple clamps from a 2004 KX250f for a newer look. I used the '02 stem with the clamps.
6. Rear wheel is the 18" KDX wheel using the KX spacers.
7. Kick lever is also from the '87 KDX, although I may go with a KX250 kicker later.
8. I am running the KX125's TMX 38 carb. I had to lean it out a lot on the pilot jet, but I am very happy with how it runs. Tons of low end power.
9. I'm using the KX's air box with no mods.
10. I'm using the KX's coil with the KDX wiring and CDI. I removed the voltage regulator since I don't have lighting. CDI is mounted in the airbox.
11. I re-used the KX's water hoses.
12. New kickstand is bolted to the swingarm.
13. I used a GPR steering stabilizer from my KX500. I had to ream out the frame mount to fit the KX steering head.

[don46]

Ok, so I finished the mock up and test ride, as I suspected this is going to be an awesome bike, it will lug like a tractor and is super lite. I need to strip it, redo the suspension, get the frame powder coated, using a set of Rad hubs and A60 rims, they came off a 450 so I'm using the 4 piston oversize braking caliper to fit the 45-0 rotor and custom building spacers, and on to the next project. I picked up a 07 450 chassis that will become another 500af.

attached photos are from my phone so excuse the quality

Ok so I guess I can't post a picture in the text