Install 2001 forks on a 1989 yz250

A few months ago I replaced the front springs with some springs from a KDX Kawasaki. The 89 YZ springs

are hard to find and the KDX spring is available in spring rates for my weight but 38mm shorter. This worked

well and the front was no longer bottoming but I love to tinker. I found a set of 2001 forks on eBay for $40.00

and I decided to convert the 89 forks to 01. I knew that I would need to change the triple clamps since the

2001 forks are 46mm and the 89 are 41mm. This would also require a new front caliper, wheel, axle and rotor.

I spent some more time on eBay and shortly found a 99 that was being parted out. The 1999 front is almost

identical to the 01 and I got more parts for cheap. While I was at it I ordered some front springs for my weight.

I pulled of the original 89 forks and triple clamps. I discovered that the 99 uses a different method of adjusting the steering bearings than does the 89. I also noticed that the 99 uses a different lower roller bearing. The 89 bearing part numbers are: both 93332-00078-00, the 99 uses the same upper but a 93332-00081-00 lower. This would require a different lower bearing and race. Getting the race out of the 89 steering stem turned out to be quite a challenge. I tried the suggested method of knocking it out from above with no success. I got a wheel puller and put the jaws on backwards as in the picture. This had just enough grip on the outer race to pull it out.

Once I got the old race out I needed to get the new race in. I got a long piece of threaded rod and a round steel spacer that happened to be the same as the race OD. I ran the threaded bar through a piece of bar stock and drew the race into place. I gave it a few taps as I went and it pressed in fine.

With the bottom race installed it was time to install the 1999 triple clamps. Since the top bearings were the same between years I installed a new 89 bearing in the top without changing the race. I know I should change the race when changing bearings but after all it doesn't get anywhere the load that the bearing was designed for. I reused the original top seal from the 89 but you can see in the picture that there is a thread gap between the top seal and the top nut. This will need to be corrected.

I made up a bronze spacer to fill the gap. Unlike the 89 which has two spanner nuts that are locked together. The 99 has only one nut that is sandwiched between the bearing seal and the top clamp. The top clamp keeps it from backing off. There is a small counter bore in the bottom of the top clamp to accept the unused threads. With the spacer installed the top nut should be torqued to 27 ft lbs loosened one turn and tightened again to 5.1 ft lbs.

With the top triple clamp installed you can see how the nut is retained on the 1999 forks. This is clearly a better design than what was on the 89 assembly. The top clamp nut should be torqued to 105 ft lbs but don't do it yet. For now leave it hand tight until the forks are installed. The forks will be needed to center and align the clamps.

After I got it all together I noticed that the 1999 lower clamp was missing a hole for the number plate mount. The casting has a boss but it is un drilled. I also discovered that the later clamps use a completely different number plate mounting. This is probably the only reason to use a 1999 clamp set over a 2000 or 2001. The front fender mounting is exactly the same as are the steering stops.

There was one remaining area of interference. I installed the front master cylinder from the 1999 front brake but the lever hit the throttle casing. I could have corrected it by sliding the master cylinder towards the right enough to clear. This would have left the conversion looking a little strange so instead I decided to use the 1989 master cylinder with the 1999 front brake. The 99 hose bolts right up to the 89 master cylinder.

The completed conversion. 2001 front forks, 1999 triple clamps, front wheel, axle and brake caliper. 1999 front caliper mated to existing front master cylinder and lever. I added a 1 1/4 inch spacer to the bars while I was at it since I am about 6'4". I think the conversion came out real good, I now can get a good spring selection and have a much more current and tunable front suspension. 1989 was the first year for the inverted forks and I always felt that they were very harsh on the small stuff. I can't wait to give it a try. Yea, I know, the front tire is flat in the picture.