Which of these brand new forks for USD conversion?

[catuk]

Hi, I've got a lead on some brand new forks that I can pick up very cheap.

They are 1988 CR125, CR125 1991 (USD), CR125 1993 (USD) and CR250 1994 (USD).

I've presently got a 1985 XR250R which I'd like to upgrade the front end of.

Could someone please shed some light on which of the forks would be the way to go with?

Would I be able to keep my XR front wheel,speedo and brake calliper with either of the above forks?

I have a friend who has a CNC machine and lathe for any possible machining needed.

Very grateful for any tips and advice:)

[honduki]

Hi the 91 set worked well on my 91 XR 250 R. Had to press the XR steering stem into the CR 125 triples. Used XR front wheel and brakes but a CR caliper bracket. Didnt keep the speedo as bearings larger for CR axle

[catuk]

Hi Honduki, thanks for the info on what you did to yours.

Do you mean you used your XR brake calliper with the CR bracket?

You had to put CR bearings in your XR front hub to accomodate the CR axle?

[catuk]

So if I got the 1991 CR125 USD forks with the CR125 triples, pressed my XR stem into the CR triples, got a CR caliper bracket ( still use my XR brake calliper ?), put CR bearings in my XR front wheel to accomodate the CR axle ( can't use my XR speedo gear ? ) Is that roughly right?

[Chuck.]

The CRs used the same stem bearings as the XRs up thru 89 (26x47mm,#91015-425-832), so all you need are spacers (or washers) to adapt the CR stem to the shorter XR steering head. In 90 Honda went to a larger lower bearing (30mm ID,#91015-KZ4-701), check with All Balls they may have a conversion bearing for the lower.

As for wheel bearings the XR250s used 15x35 (6202), the 84-94 CRs used 17x35 (6003). Check part fiche on candidate wheels, the standard wheel bearing number will be in the part description.

In the late 80s Honda changed brake pads on the XRs and CR to a type with a single pin hole on one end, so late 80 and on calipers should interchange.

Check the online part fiche on your candidate parts, The wheel bearing description will have the standard metric bearing number, in this case 6202 or 6003. Also check the brake pad part number for the calipers, the late 80s and on have a single pin hole on one end, the earlier calipers used a pad that had two holes on the top. Common pads indicate common caliper family.

Edited October 18, 2011 by chuck4788
Added bearing info

[JohanChaves]

I think calipers are the same, even the caliper braket, what changes the position is the mounting holes on the fork leg, not 100% sure though I have an entire 04 WR450F front end on my 250l and compared the calipers and brakets, were absolutely the same. Save for some cooling?? grooves the WRF caliper had (most modern calipers have it anyways)

[valvesrule]

The CRs used the same stem bearings as the XRs up thru 94

Hey Chuck the upper is the same but the lower bearing is larger on the 89 up CR USDs. The 88 & earlier cartridge forks are the same bearings as an XR top and bottom though.

[catuk]

Thanks so much for your input guys! I really appreciate it.

I've taken the plunge and the brand new 1991 CR125 USD forks will be shipped to me middle of next week. I've got a new matching 1991 stem and top bridge coming as well.

Am I right in that I'll need to press my 85 XR250 stem into the 91 CR125 stem and use 85 XR250 head bearings upper and lower?

I need a 1991 CR125 front axle and also put new 1991 CR125 bearings in my 85 XR250 front wheel to accomodate the CR axle?

And I need the 91 CR125 calliper bracket to still use my 85 XR250 front brake calliper?

Big thanks.

[valvesrule]

Your stem will be too small on the bottom press fit and will need a bushing made to fit. Doing this way eliminates the spacers. I've found it easier to just turn the CR stem to fit an XR/CR top bearing. The spacers will still be needed with this option. Also found it's just easier to use CR wheels. The calipers are the same but the CR bracket has to be used. Incidenetally the 92 up forks were rated better than the 89-91s.

[catuk]

Hi valvesrule,

So one way is to remove the CR stem and then where the bottom of the XR stem is hidden in the bottom fork clamps add a bush that fits inbetween the XR stem and CR bottom fork clamps......which top/bottom bearings with this option?

I'm a tad confused about the other option....do I turn the CR stem all the way from top to bottom and use top and bottom XR bearings and how big are the spacers/where do they go?

I'm sorry if I come across as a bit slow on the understanding, until I have the forks in my hands it's a little harder to visualise what you mean.

Thanks.

[honduki]

If you get the XR stem pressed into a bush in the CR clamps you use the xr steering bearings. I found this to be a better setup than using spacers above the top clamp using the CR stem, more rigid. I liked the 91 forks, the wheel comes off easier than 93 ones. I dIdnt like the 93 forks I tried with the CR stem setup but maybe the springs were too soft, they had been cut and a spacer added. Also the top clamp was too high imho this way. If my 91 forks werent damaged, chrome flaking off Id still be using them rather than XR400 forks on my 02 XR250R

[CHIEFCULPRIT]

When I put a 94 CR fork on my 94 250L the head was tube was too short for the stem. I used the All Balls conversion bearing, but as I have heard they don't make them anymore. They told me they machined the OD of the CR race to fit the XR head. I had to use the CR stem otherwise the clamps would not cinch on the fork properly (due to tapering). Also I had to machine down under the threads for the top bearing to slide down into the top race. Then 7/8" was left so I machined a spacer at 3/4" to go between the top seal and clamp. I didn't put any spacers at the bottom because it was a perfect fit to use the CR stops on the bottom clamp. I used a complete CR front end: wheel, brake and lever. The calipers are the same and the either lever works the CR just fit better. I had to have a custom brake line made for the extra reach due to routing around the headlight and the steel braided lines add a lot more stopping power. You will need the CR caliper bracket. Not a hard conversion just time consuming, very worthwhile.

[Chuck.]

Hey Chuck the upper is the same but the lower bearing is larger on the 89 up CR USDs. The 88 & earlier cartridge forks are the same bearings as an XR top and bottom though.

We may be looking at different part fiche but "this one" shows the same bearing top and bottom on the 89 CR250R (91015-425-832). This bearing measures 26x47 and is very common on Honda dirt bikes, it is a standard 25x47 metric tapered roller bearing with a 1mm larger ID (All Balls sells them). All Balls also has custom bearings to adapt stems to steering heads, call Alex @ 888-228-3323. In 90 the lower bearing changed to 91015-KZ4-701.

But more important is your comment points out the problem of finding replacement forks:

For CRs, and others, forks may be the same across several years but the stems, and/or triples may change. Another example is the CR conventional forks, all the same size across many years, but the 250s changed to cartridge internals one year earlier than the 125s. All of this makes it difficult and confusing when shopping for a front end.

To further confuse the issue sellers (knowing and unknowing) don't always post correct info about model year so be careful when buying.

Edited October 17, 2011 by chuck4788
added info

[catuk]

Thanks for the replies; without you guys I'd be lost:bonk:

The front wheel bearings on my '85 XR250 are 62020U (15.35.11)

The front wheel bearings on the '91 CR125 (I have the forks,axle for this etc) are 6003-SH2 (17.35.10)

Can I put the CR bearings in my XR front hub to allow the use of the CR front axle?

Here's a picture of one of the brand new forks

[catuk]

Well stone the crows!

I bought a new 1991 CR125 stem to swap in my XR stem. Took them up to my friend's workshop and preceeded to "try" to press out the CR stem. My m8 lathed up a collar to support the stem from underneath and lathed up a bar to go down the centre ot the stem to prevent any bending.

9 and 1/2 tonnes of force and the bloody thing wouldn't budge! and yes we were pressing in the right direction.

Only thing to do next was to drill out the stem from the bottom end as far as the snap ring and then cut off the stem above the bottom fork bridge and then carefully hacksaw two slits and back to the press to get the last of it out.

We think the snap ring was what was causing us the grief.

My friend is machining me a new stem the same as my XR one to press into the CR stem next.

Just a couple of videos and pictures, in the one picture you can see the snap ring.

Click on the two pictures below to play video.

[CHIEFCULPRIT]

Ok, Something seems out of wack here. The stem should of pressed right out no need to machine it out.

[valvesrule]

Every stem I've pressed out took most of a 20 ton press. They must heat the triple clamp a hell of a bunch to fit them up at the factory. If you check the interference fit you'll be amazed how much oversize on the stem is for both the clamp and the bearing. Chuck, I've read allballs no longer has the conversion bearings and won't be restocking them. You're right on the 89 cr stems, it's 90s that got the larger lowers.

[Chuck.]

Thanks for the update on AllBalls.

And yes bearing swapping is an easy way to adapt wheels, I just swapped bearings on a RM rear wheel to use it with a 17mm axle on my XR, I had to fuss with spacers because the RM sprocket, bearings, and rotor use different offsets than the XR.

I agree that it often take more than 10 ton to press out a stem. On my stem replacement I cut the XR triple to remove the donor stem. The XR stem was too small for the CR triple bore so I installed it using Loctite/Permetex repair compound, good for 5000psi and gaps to 0.018". After a thorough cleaning I assembled the forks, both triples, and the stem; then let the compound cure for 24 hours. Just finished two seasons of riding without any problems.

[catuk]

Whilst I'm in the middle of this fork upgrade, can anyone advise whether it would be a sensible idea to maybe put a stiffer spring on the rear shock to kinda compensate the stiffer front end and where to buy a new spring? Apologies if I'm barking up the wrong tree.

[JoeBlow Kokomo]

Whilst I'm in the middle of this fork upgrade, can anyone advise whether it would be a sensible idea to maybe put a stiffer spring on the rear shock to kinda compensate the stiffer front end and where to buy a new spring? Apologies if I'm barking up the wrong tree.

How much do you weigh? The rear end is set up stiffer than the front, so it's ok for 170-180lb rider (depending on the riding of course). If you're over 200lbs it's an definite must do.

Race Tech and Eibach make and sell springs, but any of the discount mail order places can order them for you. $110-130 (US, here)