Inverted forks off crf250?

[planetwister]

My uncle has a blown up 05 crf250 could I use the front forks on my 97 xr600? And maybe rear shock? More interested in the inverted forks. Thanks!

[jamracing]

You could move the whole front end, but I'm not sure about the steering head bearings... It'll definitely change the steering (less trail). With the shock, you'll have to measure from eye to eye, and even if it fits (how it mounts to the frame/linkage) , you'll probably have to revalve it and put a heavier spring on it.

Keep us updated...

[planetwister]

Ok thanks man. I'm getting the aloop kit so I'm goin for more of a "MX" look. So I'm guessing the fork tubes aren't the same size? Maybe I can pull up a schematic and see if the hear bearings are the same

[planetwister]

Doesn't look like there the same size

[Horri]

http://www.advrider.com/forums/showthread.php?t=774934

 

http://home.comcast.net/~ledrocnoc/CRFClampMods/

 

Couple of things worth reading above,,both relevant ..Makes no difference whether it's 250/450 forks,,same stuff..

Edited October 4, 2013 by Horri

[planetwister]

Some good info there! Thanks man that's all I needed

[Horri]

Yeah some good info there..I just purchased a set of 450 forks myself..One's got a rooted damper rod (snapped thread) so I need to get that fixed somehow..Think I'll be going down Elsalvadors path to install when I have the damper fixed or can get another rod from somewhere cheapish.. Whacking out the CRF stem and using the 600 one seems logical and easy..least I gather that's what he did prior to selling the beauty.. ?

Edited October 5, 2013 by Horri

[heart_of_darkness]

When picking forks, the two factors are valving and spring rate.  All CRF forks will have too soft springs; CRF450R forks have the stiffest springs which would be marginally useable as-is.  For valving, the 450x forks will come valved closest to correct for the heavy XRs.  No CRF forks are really drop in correct for the XRs.  Springs are $100 and easy to swap out.  Valving can be changed for free, if you do some online research and learn how to do it yourself; if you pay a shop, it'll be several hundred dollars.

 

All CRF forks are about 1 inch too long for an XR, so need to be internally shortened.  If you pay a shop to have it done, a revalve shouldn't add much to the cost.

[Horri]

Well I won't be shortening mine,,I;ll just raise them in the clamps.,surely that's possible,.anyway,,shims etc,,below is the madness and knowledge.,Prepare for a lot of reading,,Thankfully I am not a pro rider so won't be getting quite as carried away as people in the below.,Shim stacks for Africa..way over the top for a Joe Average like myself..

 

 

https://www.thumpertalk.com/topic/327668-diy-04-450-suspension-re-valve/

 

Have you seen any threads around on this shortening business HOD,,can't say I have,,any leads to a thread somewhere??

Edited October 6, 2013 by Horri

[mastera210]

Well I won't be shortening mine,,I;ll just raise them in the clamps.,surely that's possible,.anyway,,shims etc,,below is the madness and knowledge.,Prepare for a lot of reading,,Thankfully I am not a pro rider so won't be getting quite as carried away as people in the below.,Shim stacks for Africa..way over the top for a Joe Average like myself..

 

 

https://www.thumpertalk.com/topic/327668-diy-04-450-suspension-re-valve/

 

Have you seen any threads around on this shortening business HOD,,can't say I have,,any leads to a thread somewhere??

You can not raise forks that much in triples as they have a taper on the tubes. And if you dont shorten them 1in it will turn worse than stock! And to do it you need to know what you are doing and have tools to do it best left to the pros plus while they are doing it rebuild the forks new bushings seals revalve. I know I have been told I go to extreams but I learned the hard way best to do it right first time or it will cost more in long run! And you also need yo bring the shock up to the level of new forks they HAVE to work together. On mine I have 700 dollars in suspension work alone! Thats revalving rebuilding forks shock. Again I know I go off deep end but my stuff is right! I HATE that saying well thats good enough!! 

[heart_of_darkness]

 

The twin chamber Showa forks are, luckily, much easier to shorten than many others.

 

Just raising the fork tubes 1" in the triple clamps is extremely dangerous.  If you then bottom the suspension while riding, the top of the tire will bind against the under side of the fender, instantly stopping the wheel from spinning.  The whole bike then pivots around the front wheel, throwing the rider over the handle bars in a superman impression.  If it happens at enough speed, it can actually pile drive the rider head first into the ground.

[ta3ff]

I have 05 CRF450R front end on my XR6 and I love it. No more head shake at high speeds. No revalve just experiment with the clickers until you find what works best for your style of riding. I like the compression a little on the soft side and the rebound just before it feel to springy. Again, all personal perference.  I used All Balls bearings kit. Quick and cheap, but a little on the dangerious side. If not shimmed correctly it will losen up or worse.

 

You might as well add the CRF FCR carb to it and have a real beast underneath you.

Edited October 7, 2013 by ta3ff

[JoeBlow Kokomo]

When picking forks, the two factors are valving and spring rate.  All CRF forks will have too soft springs; CRF450R forks have the stiffest springs which would be marginally useable as-is.  For valving, the 450x forks will come valved closest to correct for the heavy XRs.  No CRF forks are really drop in correct for the XRs.  Springs are $100 and easy to swap out.  Valving can be changed for free, if you do some online research and learn how to do it yourself; if you pay a shop, it'll be several hundred dollars.

 

All CRF forks are about 1 inch too long for an XR, so need to be internally shortened.  If you pay a shop to have it done, a revalve shouldn't add much to the cost.

 

 Too soft fork springs?  All I've seen listed were either .45 or .47 fork springs. That's recommended for 225lb range for XR's.  Dead on perfect for me. ???

[JoeBlow Kokomo]

 

The twin chamber Showa forks are, luckily, much easier to shorten than many others.

 

Just raising the fork tubes 1" in the triple clamps is extremely dangerous.  If you then bottom the suspension while riding, the top of the tire will bind against the under side of the fender, instantly stopping the wheel from spinning.  The whole bike then pivots around the front wheel, throwing the rider over the handle bars in a superman impression.  If it happens at enough speed, it can actually pile drive the rider head first into the ground

 

  LOTS of guys here with this mod, including me and I've not heard of ANY type of similar incident, nor of engineering guys warning of it. All bikes will bang the tire against the fender at full compression.

I think you are being a bit dramatic about the "danger". 

[heart_of_darkness]

 Too soft fork springs?  All I've seen listed were either .45 or .47 fork springs. That's recommended for 225lb range for XR's.  Dead on perfect for me. ???

 

Different styles of fork, and different valving setups, require much different spring rates for a given weight rider/ bike.  Old school forks used soft springs but more restrive valving; the trend with modern forks is to stiffer springs.  So while .47 is probably correct with the stock XR6 forks on a 300 lb bike, that same spring rate in dual chamber forks is correct for a 230 lb CRF bike with a 170 lb rider.

 

CRF forks with too soft .47 springs will still be vastly better than the stock forks.  But they'll be better yet with stiffer springs.

Edited October 8, 2013 by heart_of_darkness

[heart_of_darkness]

  LOTS of guys here with this mod, including me and I've not heard of ANY type of similar incident, nor of engineering guys warning of it. All bikes will bang the tire against the fender at full compression.

I think you are being a bit dramatic about the "danger". 

 

Lots of guys here with this mod have never bottomed their forks.

[JoeBlow Kokomo]

Lots of guys here with this mod have never bottomed their forks.

 Hmmm, maybe.  But a fair amount also play with them on motocross tracks, especially after this mod.

And they are liked most by high speed, desert type riders who i would think would have plenty of experience, especially if the springs are so soft.

 

I have stock .47 springs in my usd on my 350 and tuned and .47 eibach aftermarket springs in my 400 tubes. 

Both feel comparably sprung to me and I've spent a lot of time comparing them to see if I prefer one over the other. 

What rate spring are you saying I should have for 230lbs of rider and xr400 weight.? 

Edited October 10, 2013 by MindBlower