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Forks: XR650R vs. XR400


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I've thought about those a few times as well. I asked once on here and was told they would not be an upgrade. I still think they would be IMO and I'd love to hear from someone who has tried it or has at least rode the 650 enough to speak on the fork action, IF it were on a lighter bike. 

 

They are a bigger diameter (+3mm), have the same amount of under hang as XR4 forks and they were intended to be on a heavier bike so the damping and springs are most likely already set up stiffer than the 400 forks. I'd try a set if I could find a screaming deal. I think Emig racing lists the bearing sizes on one of their conversion charts. If I remember right, one bearing matches and the other does not.

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Here is the chart I was thinking of. It's from All Balls not Emig.

 

https://www.allballsracing.com/index.php/forkconversion

 

Looks like the XR400 has the same size bearings top and bottom. 

 

26mm ID x 47mm OD x 15mm

 

The 650R has the same top bearing ( 26x47x15) but a larger bottom bearing (30x51x15).

 

So all you would need is a bottom bearing that is 30mm (650R ID) ID x 47mm (400R OD) OD x 15mm

 

It loos like they have a 30x47x12 listed as available. Not sure if being 3mm thinner would screw anything up or not.

 

http://www.allballsracing.com/media/productshowcase/AllBallsSteering%20Bearing%20Size%20Chart.pdf

Edited by michigan400
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I cant tell you about fitment (650r forks)to Xr4 but we have been Using Xr650r forks on our 04/11 WR450s.We use stock Wr triple clamps.With custom made spacers to slide the 650 forks in Wr triple clamps.Stock Xr springs are .43 perfect for the WRs with big tanks.Stock Xr650r forks work bad for our use (way too hard riding) We change the comp/rebound/mid valving,and many more mods.We keep the .43 springs.They work better (more plush) then any of our Wrs re-valved with USD forks.There is nothing wrong with stock Xr4 forks with mods for trail riding.We have one Wr 450 with Xr4 forks 11in travel/rear shock spacer to reduce it to 11in travel (for short rider) The mods on the xr4 fork work great. The xr650r forks inside are like The USD forks but they are 12 in travel BTR

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Good info BTR!! Thanks!!

 

It's really just have to fun thinking it through and if a good deal comes along might be something to mess around with and try. Those of us in the snow belt have a few months on our hands where we cant ride so we gotta do something to entertain ourselves! LOL!!

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Then you have lots of time,or come to Baja and ride.You can make spacer for 650 forks and reduce travel to 11in.To match rear of xr4.If cost many $ to do this conversion to our Wrs.My own Wr is apart It already had spacers for Cr500 forks that I have been using for over 25 years on many bikes.After riding our first Wr with 650 forks.They work even better then my,Cr forks.To mount them to my 11 my spacers need to be bored out 3mm more.On front wheel two ways we do it.To mount Xr4 wheel to 650r fork,you just need 650r axle (half in longer then xr4 axle) To mount Wr450 wheel to 650r forks,you use xr650 axle,and make spacers to ride inside Wr450 bearings.As many of you know Im not a fan of usd forks.Baja seems to love to blow the seals.To help this problem we use seal savers full length,and wrap plastic guard.All around bottom of fork.I got mine Xr650 fork on Ebay for 180.00 shipped,Axle shipped was 24.00.New seals cost me 35.00.The heavy mods re-valving about  about 180-200$. Worth every penny,to not have to deal with USD forks.Only problem if I let one of my buddys with USD forked bike ride mine.They take off,wont give it back till, 100 miles later .

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Here is the chart I was thinking of. It's from All Balls not Emig.

 

https://www.allballsracing.com/index.php/forkconversion

 

Looks like the XR400 has the same size bearings top and bottom. 

 

26mm ID x 47mm OD x 15mm

 

The 650R has the same top bearing ( 26x47x15) but a larger bottom bearing (30x51x15).

 

So all you would need is a bottom bearing that is 30mm (650R ID) ID x 47mm (400R OD) OD x 15mm

 

It loos like they have a 30x47x12 listed as available. Not sure if being 3mm thinner would screw anything up or not.

 

http://www.allballsracing.com/media/productshowcase/AllBallsSteering%20Bearing%20Size%20Chart.pdf

 

 Believe that's the same size used in USD fork swaps. You can get 1mm shims from McMaster Carr and elsewhere, use 3 of them to make up the thickness. 

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That's what I was thinking also. Just get or make a shim. I need to look up the DRZ bearing sizes. I've heard many people say those are some of the best quality conventional forks you can get. Plus they are 49mm units. No fork brace needed on those big legs.

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That's what I was thinking also. Just get or make a shim. I need to look up the DRZ bearing sizes. I've heard many people say those are some of the best quality conventional forks you can get. Plus they are 49mm units. No fork brace needed on those big legs.

 

DRZ400 forks take 30mm ID x 52mm OD x 16mm thick bearings

 

DRZ forks on XR400 would require 2 bearings from all balls at 30mm ID x 47mm OD x 12mm thick (available from all balls). And of course, the entire front end of the donor bike.

 

So with available bearings and a couple shims, you can also have either XR650R forks or DRZ400 forks on your XR400 besides the known USD Showa units. It's possible on paper anyway. Actual results may vary and I am not saying these forks would be "worth it" to use. But they might be!! LOL!!

Edited by michigan400
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