KDXRIDER.NET

Hello all, I'm new to this forum, and dirtbikes in general. I have a 1986 kdx80 and someone just threw a kx80 fork with disc brakes . I'm rebuilding it because it's in poor shape. My problem is with the fork, it has tapered bearings , but the kdx frame uses roller ball bearings. It was just put on the frame without the races for the kx tapered bearings and was sloppy as ther was nothing for the tapered rollers to ride against. Did anyone ever convert a kdx 80 frame to tapered fork bearings? Or should I use the kdx triple tree with the kx tubes? Just looking for a proper solution to this problem. Thanks

I would probably try to do it like any other fork swap. See if you can press the stem out of the KDX triples, press that into the lower KX triple, and use the KDX stem and bearings with the KX forks and triples.

Makes sense?

Welcome to the forum, btw :).


J.

The tapered bearing would be more durable (jumping), but the roller bearings would work fine for trail riding.

Do you have the KDX triple clamp? Would the KX forks fit the KDX clamp?

You will have to figure out for yourself to see if the tapered bearing seats would fit the bike frame.

To figure out the seats, measure the inside of the frame where the seats go, or remove the old ball bearing seats with a drift (punch). Take that and the roller bearing to a bearing shop and have them look up what seats go with the bearing to see if they will fit the frame. If they do, you can use them. Buy new bearings with the seats.

Double check to make sure the races fit snugly before you mark them up in case you measured wrong and have to return them. Drive (hammer) or press (c-clamp) them in using a socket thet matches the outer diameter of the race.

Assemble the triple clamp with the bearings (apply grease to them) in and make sure you can get the nut to tighten down with some resistance to turning the triples (preload). If the nut bottoms out before you get preload, you will have to find or make a washer to take up the extra space. You want just enough preload so that you can just feel it a little through the handlebars as you try to turn them on a stand.

Thanks for the help, I really appreciate it. I was looking for a upgrade kit to tapered bearings , but no one makes one for the kdx80. I don't have the kdx triple clamp or stem. I might get one and try to press out the stem or see if the fork tubes fit into it from the kx80

Worry to revive a dead post, but I recently put a '97 KX80 front end on an 87 KDX80.
What I did was make a bushing that would fit on the KX80 stem and allow a tight fit for the KDX80 bearing race (lower race, top fits fine as is).
I then used the ball bearings and races from the KDX80.

The other issue was when I tried to assemble everything, their weren't enough threads on the stem for the last nut to be fully threaded. I ended up milling the lower nut to about half it's original thickness and everything went together fine. I also shortened the forks 4" with a spacer and use KX65 springs which are the same rate as the KDX, but about 4" shorter.

If I were to do it again, I'd probably put the KDX80 stem in the KX80 clamps. That would require a bushing to take up the space as I think the KX80 stem is fatter were it fits into the lower triple clamp. You'd also have to machine a slot for the retaining ring. Easy for any machinist to do.