HRDROKN

Hey Guys...

I just wanted to share with you all my 99' KX125 / 03' KDX220 build.

I had picked up a fairly clean 2003 KDX 220R a few months back for $900. I had been riding this bike comparing it to my 300exc... if there is such a thing. There are a few things I like about the KDX and many things I like about the KTM! The KDX is easy to ride... the KTM can be a handful and I feel it the next day, but she handles so much better at speed. So rather than my original plan of a KX fork conversion etc. I picked up a 99' KX125 for the best of both worlds? Of course that is only what I have read...

Pics coming....

HRDROKN

Started stripping down the KX chassis early this morning and noticed that my lower motor mounts are of the double variety? Thought I read that that was different in the 99' compared to the 00'-02' frames. Not a big deal by any means... wonder if it was a change that some of the later production frames received in that year?



Also ordered up a 18" wheel and spokes to mate up with the KX hub.
I think I will take the forks and shock up to Dicks Racing for a rebuild/re-valve, since they are local.

HRDROKN

The KX motor comes out heading for Craiglist....

HRDROKN

And now the KDX motor comes out.....

HRDROKN

After getting a first hand look at whats needed, I see that the actual cut on the swing arm is the least critical of the operation... you can do this with a hacksaw and file!

Did all the measurments and 9mm on each side is sufficient....

HRDROKN

The greatest concern and area to get correct is the swing arm bushing. It has to be fairly darn close, as it will set the overall compressed length.



Drilled the cases by 64ths to 21/32's then used a 17mm ream to finish....

HRDROKN

Figured out a good way to hold the bushings while cutting.... I used the swingarm bolt in the vise!



I used a carborundum disc to make the cut, then a flapper wheel to clean the cut, and then a course stone to the target dimension.

HRDROKN

With all the swingarm mods out of the way, it was time to see how she was going to line up in the chassis...



And would the lower mounts line up..... it was close! So I will cut the lowers out and fab new ones....

HRDROKN

Interesting...

Ive been playing with motor location as it compares to the pipe, airbox and fuel tank.... looks like things fit better the more you rotate the motor forward.
The boot on the airbox is too long and it seems as though the KDX boot would be a better fit....



With forward rotation, the pipe just misses the down tube.... a little dent in the pipe should provide desired clearance...



When you rotate the moto forward you lose the lower mount position...



And I have a solution....

HRDROKN

Needed to remove the rear headstay to fit the tank in place.... this is how we do it old school!





I will clean it up before I send it off to RB... along with the carb.

HRDROKN

With the motor rotated further forward as the goal... I put the swingarm, wheel and chain on.... moved the motor around and I can't really tell much difference in regards to pressure on the chain guide, at least no more/no less than taking a tooth off the front sprocket.

So I guess I will keep the motor rotated forward and work on some new lower mounts...

HRDROKN

After trying several different ways of configuring the airbox, I think the best solution is to use the stock KDX box... it requires one of two modifications to fit correctly.
First and the best solution is to cut the stock KX airbox mounting tabs off and re-weld them to match up with the KDX mounts. You can see it in the pics. EDIT: This is not the best way to go as those tabs are used for the fender also! So the second way is the best!
Second, modify the stock KDX box and utilize the KX airbox mounts on the sub frame as is... I went this route as I'm not set up to weld aluminum. After cutting the KDX box for clearance I will fab some aluminum plate to cover the holes and provide for mounting.

Byro

I had a 02 KDX for a year or so, it was good bike, I had the forks and shock re-valved to KX250 specs, Pro Circuit pipe and Boysen reeds. I really liked it for the riding we have out east (real tight technical single-track) The only problem I had with it was the clutch would get hot and start slipping. Ending up selling it and getting a woods prepped YZ426f.

HRDROKN

Finished off the KDX airbox mount.....

HRDROKN

I set it up with shock in place before taking all the suspension to Dick's. Hard to see from this pic, but there is at least .125" all the way around.



Here is the fender without the bolts in.... but they line up and the KX fender fits the contour of the box perfectly!