At some point early this year I convinced myself that a pair of USD forks were absolutely necessary for my personal happiness. It probably had a lot to do with the updated looks, it might have had something to do with wanting “tighter feedback” from the bars I can’t remember I was blind to reason. I found what I thought was a pretty decent deal on the forks, triple clamps, guards, and front brake from a 94’ KLX250 and decided this would be the route I took
Like many of you I planned on doing some riding/racing this spring, so the parts were picked up for a “down the road” project. Well you guys probably heard of this COVID thing going around and needless to say this project moved up the list. Maybe this way when things open back up my new forks can be done, installed, and yard tested.
I got the triple clamps cleaned up and put a shine on them to help shed dirt when washing. I also found the previous owner had mashed over one of the steering stops. I had a neighbor with TIG welder get some aluminum built back up. Then I had him add some extra material on the faces that contact the stop. I read the KLX conversion requires just a bit of extra material to keep the fork tubes off the tank.
I took the inner race from the old lower bearing and took .005 off the inner dia. This allowed me to flip the lower triple clamp in a vice and use the repeating percussion press to install the new lower bearing. I almost didn’t replace the outer bearing races on the stem bearing because the top one looked so good. The bottom one didn’t look nearly as good, so they wound up getting replaced before the triple clamps got installed. After that I put the fork tubes in and did some tuning on the material that was added to the steering stops to get as much turning prior to contact with the frame or radiators as possible.
The KLX bar clamps are swept back quite a bit more than the KDX clamps were and this seems to move the bar centerline behind the fork tubes quite a way. From what I read it seems “ideal” bar position is directly over the fork caps. I picked up a set of ROX risers to help with some ergonomic issues. These risers should allow me to move the bars forward enough they are positioned directly over the fork tubes. They will also adapt from the stock 7/8” to my 1 1/8”. Hopefully the added height will make standing a little easier without seeming too tall sitting down. I don’t expect to get the full 2” additional height because the bars are rotated forward, nor did I think 2” was needed.
For the forks I went with All Balls for the seal and bushing kits, Maxima for the oil, and Race Tech for the springs. I went with a .46KG/mm spring this seemed correct per the Race Tech calculator. I adjusted the rider weight to account for the reduction in bike weight from the KLX to the KDX. The stock KDX forks only have about 5hrs on their rebuild with 42KG spring and those felt pretty good but a bit soft if pushed harder. I had to sand the spring guides from inside the fork quite a bit to get the thicker Race Tech coils to slide over them easily. I used a 3D printed valve seal driver to get the bushing and seal seated properly, it worked surprisingly well. I left all the valving unmodified and filled the inner chamber only to 120mm as described in the Race Tech instructions. I set the damping clickers to 10 for initial testing. It all went pretty well no big surprises with damage or anything like that.
With the fork legs fitted I moved on to assembling the rest of the odds and ends. I used the front brake from the donor bike and installed the old lower for guards as I’m still waiting on some new ones to come in. I picked up a 19”KX450F front Fender and Polisport headlight assembly. I couldn’t bring myself to put Polisports big black rubber brands around my fresh new forks, so I fabricated a sheet metal frame that uses original mounting positions. The plastics didn't match up great on the shade of green. I know some purists don’t care for this mostly aesthetic update, but I think it makes the bike look a bit more modern.
I didn’t get much riding in between the rain but the forks feel good and the handling seems more responsive than it was. I like the bars positions over the fork tubes but I am still on the fence with the change in height. This was not a difficult swap. I think most people would find themselves capable.
I’m sure this has drawn some heavy sighs as they are not the preferred KX forks and lack rebound adjustability. It’s important to note here that I am a far more capable mechanic than rider. I probably wouldn’t know rebound being out of adjustment if it slapped me in the face. 94' KLX250 quick swap
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Re: 94' KLX250 quick swap
Hey! Congratuations. It looks good. Thanks for the report.
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