KX500 - 2006 CR250 Forks and Triple Clamps

[Pile-O-K5]

I have a '94 KX500 and wanted to upgrade the suspension.

I came across the all balls racing conversion chart located here:
https://www.allballsracing.com/forkconversion
Most CR's seem to fit. The chart does not consider swapping steering stems.

Conveniently, a riding buddy of mine has a '97 CR250, so we began taking measurements. The steering stems seemed to measure out ok, and the all balls conversion chart lists the CR250 as a potential swap. The chart also includes CR/CRF's/CRFX out to '18. RM's and RMZ's also fit out to '18. I have a KDX220 that I will be trying a RMZ conversion on later this year. Will post the results here since it should be similar to the 500 for fitment.

I came across a good condition 2006 CR250 fork and triple clamp setup for relatively cheap and is a good enough upgrade for me and the riding I do. The swap will also require the use of the CR wheel and brake.

I bought the conversion kits from all balls for the upper and lower steering stem. Here is what came in the box; each box contained the bearing and cup required for the swap, dust seal and 2 washers of different diameters and depths. Good stuff, 3 of the 4 washers in the two kits are not needed.

What's in the box?


This swap is/was relatively drama free. One of the washers from the conversion kits is the correct depth for the upper bearing race. It is needed as the supplied bearing is 3 mm less wide than OEM. However the washer needed to be modified as follows, the inner diameter needed to be increased to allow the bearing to seat into the cup properly and the outer diameter needed to be decreased to allow the washer to fit into the steering race. In addition a steering stop needs to be created. My solution is to weld on additional material to the original stop tab and frame and engage the tabs on the lower triple clamp. I have it drawn up in CAD.

Fit AND Finish:









CAD:




I am not quite finished yet the swap yet. I am waiting on a brake rotor and need to pick a machine shop to create the steering stop.

I will post some pictures to show the nut engagement on the triple and how the fitment looks. I couldn't be happier with how it fits.

P.S.

I am grateful for the information on this site. Helps me keep my bike going, and improving it.

[Sandblaster]

Excellent.
I've been aware of the All balls kits for a while but never tried them.
Post pics when you can,
Thanks

[Pile-O-K5]

Original post updated with pictures.

[Sandblaster]

Very nice.
Those forks should make a nice improvement.

[Sandblaster]

You could buy this...

conversion.jpg (129.95 KiB) Viewed 12359 times

On some of the triples the angle is Alex Ward little off but works fine.
Or you can grind and polish to your preference.

[Pile-O-K5]

Thanks for recommending that. I did not know something like that exists.

[Pile-O-K5]

Progress.

I tried the trick engineering steering stop, it needs to be modified significantly, but useable. The bottom triple clamp needed a slight modification as well so that the bottom number plate mount did not interfere with the steering stop.

The steering stop and the triple clamp as it came:



I had to flip the steering stop over so that it cleared the nipple for front number plate for test fitting.

Modified steering stop and number plate mount:





I decided on about 1/4" - 5/16" clearance from the fork tube hitting the radiator cap. I may take more material off the steering stop after a couple of rides. Maybe take enough material of the steering stop to close the gap up to 3/16" or so.

The nipple on the bottom triple clamp for the front number plate can be cut down to clear the steering stop. It allows the front number plate to engage the nipple with enough material to not be an issue. The bolt for the number plate is at the top and essentially locks it in.

[Sandblaster]

Good to know.
Be sure to update us after you ride it.

[Pile-O-K5]

Ok, I was able to get a serious ride in tonight for a couple of hours. Local sand pit with the crew, mostly free riding with some large jumps. I do have a few other rides in but they were pretty tame and mostly to shake down that there weren't major issues with the swap.

Compared to the OEM fork the CR fork rides much higher in the stroke when coming into jump faces. The OEM forks seemed to easily bottom out and were not confidence inspiring. I experienced this on both the face and landing of jumps. Additionally, taking on technical climbs with abrupt transitions to the grade (flat to steep, etc.) the fork would tend to dive through the stroke at the transitions. This was more pronounced in sand and gravel. Which is likely the soft terrain adding to the feeling of the front end diving. The newer forks do not exhibit any of the above traits and were much more in line with what I expect for suspension out of a motocross bike. I believe the CR forks are much better setup for my weight and riding style than the OEM KX500 fork.

There is one handling trait the bike seems to exhibit which I found odd. I cannot place whether it is a good or bad thing and may appeal to riders differently. The first few times I rode the bike post swap, it seemed to be extremely stable at speed. Abnormally so. However, with the KX500 out of commission for the swap, I did have a lot of seat time in on my XR50 and my partners KX100. She is away in the Yukon for work, so I am able to indulge myself. The extra stability I am noticing may just be from moving back to my bike and it's larger wheels after a few weeks of not riding it. I did notice that it seems like the front tire has more ground pressure now. Besides those observations, the bike still handles great at lower speed and tight corners. Also, I did not think once during my ride today that the bike should handle better. I was able to place the bike exactly where I wanted it to go. The riding tonight was mostly 3rd gear riding, and not a lot of opportunity to really open the bike up to higher speeds.

The only revisions I am going to make is to the steering stop. Although I don't think I need the bike to turn sharper, there is room to file the steering stop down more, so why not.

Overall I am really impressed. The brakes are much better and a side benefit from the swap (Honda rotor, pads and caliper. KX500 master +SS brake line). The front number plate and fender are much more modern looking. The suspension is leaps and bounds better than OEM, I was hitting jumps and climbing stuff that I would have questioned with the previous forks, which was the main objective of the swap. The handling of the bike has not been negatively impacted at the minimum and may have been improved in many ways.

No pictures, was having way too much fun. Which is the most important part.

[Sandblaster]

Sounds great..
Yes, the last real fork update was in 1997 and remained unchanged till 04.
Now, get those forks valved and sprung for your weight.
I recommend Pro action but there is a lot of good suspension companies out there..