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2004 XR400R Spring Rate Question

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I have a 2004 XR400R and I am trying to figure out what spring rate to run. I do enduro/trail riding. I do not race it but I would say a C rider. I weigh 169 pounds with no gear, 5'10'' and run a stock gas tank. I think stock is 0.41kg/mm front and 9.8kg/mm rear. Race tech said run a 0.440 front and 10.5 rear. Factory Connection said run a 0.45 front and 9.5 rear or I could keep stock. One of the local shops said 0.46 front and 10.5 rear and another shop said 0.46 front and stock rear. Who do I believe? What are some of your recommendations for spring rates? Also what do you all think about fork braces? Thanks in advance.

Edited by bluer6

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I won't offer an opinion on spring rates but I will say that a fork brace works great on the XR. I think it's one of the best mods besides a respring and revalve that you can do.

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No two people will have the same opinion regarding spring rates. You will have to use the trial and error method to find the combo that works for you. In my opinion though, IF IT AIN'T BROKE, DON'T FIX IT!!!!!

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Ok, so I'll offer an opinion. At 169lbs, I'd start with keeping the stock shock spring. You're right at the weight range for its spec. For trail, I err on the side of plush, yet controlled. The stock fork springs have been considered to be too light for years and years and years. Makes the bike unbalanced suspension-wise. I think I'd go Factory Connections suggestion with the .45s and keep the stock shock spring.

Plan on doing any fork revalving too? If not aftermarket, at least to the shim stack mod for better hi speed compression.

Do you stand or sit when riding?

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1 hour ago, Trailryder42 said:

Ok, so I'll offer an opinion. At 169lbs, I'd start with keeping the stock shock spring. You're right at the weight range for its spec. For trail, I err on the side of plush, yet controlled. The stock fork springs have been considered to be too light for years and years and years. Makes the bike unbalanced suspension-wise. I think I'd go Factory Connections suggestion with the .45s and keep the stock shock spring.

Plan on doing any fork revalving too? If not aftermarket, at least to the shim stack mod for better hi speed compression.

Do you stand or sit when riding?

I was not planning on revalving. Do you think the shim stack mod would be almost as good? I am trying to stand more when I ride but I do catch myself sitting more.

Edited by bluer6

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2 hours ago, bluer6 said:

I was not planning on revalving. Do you think the shim stack mod would be almost as good? I am trying to stand more when I ride but I do catch myself sitting more.

Almost as good as replacing the springs with the proper rate? No. The proper rate springs support the bikes weight better and do it up higher in the stroke. Proper rate springs can be more plush than the under rated springs. Seems backwards but it's not, because of how the bikes weight settles further into the softer rated springs compression before it's supported and then any spring damping happens from there, which can make the front end seem harsh.

Are you doing the spring swap yourself or paying a shop? There's nothing technical about the compression shim stack mod. There are 12 shims, all the same size, arranged in a single stack. You just remove 6 of them and put things back together. Hi speed compression over braking bumps, rocks and roots and other sharp hits is improved greatly.

Edited by Trailryder42

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4 minutes ago, Trailryder42 said:

Almost as good as replacing the springs with the proper rate? No. The proper rate springs support the bikes weight better and do it up higher in the stroke. Proper rate springs can be more plush than the under rated springs. Seems backwards but it's not, because of how the bikes weight settles further into the softer rated springs compression before it's supported and then any spring damping happens from there, which can make the front end seem harsh.

Are you doing the spring swap yourself or paying a shop? There's nothing technical about the compression shim stack mod. There are 12 shims, all the same size, arranged in a single stack. You just remove 6 of them and put things back together. Hi speed compression over braking bumps, rocks and roots and other sharp hits is improved greatly.

I always do the work myself except suspension. I know that sounds crazy but I guess it kinda freaks me out. lol. I was going to let a shop do a refresh on the forks and the rear shock because I do not know if it has ever been touched. So I just remove 6 shims in each fork? Is refreshing the forks easy to do and what all does it consist of?

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59 minutes ago, bluer6 said:

I always do the work myself except suspension. I know that sounds crazy but I guess it kinda freaks me out. lol. I was going to let a shop do a refresh on the forks and the rear shock because I do not know if it has ever been touched. So I just remove 6 shims in each fork? Is refreshing the forks easy to do and what all does it consist of?

The forks are just a different animal than the carb that a lot of folks freak about tearing into. Just different, same attention to detail required. If by having the forks "refreshed" you mean bushings and seals too, while the forks are broke down that far, have the shop remove 6 of the shims off the compression stack.

I don't mind doing my forks, but the shock can be finicky to bleed and get right, plus needing the right tools and Nitrogen to recharge it. I've always let the shop do it.

Find a shop manual if you don't have one. The manual gives instruction on how to break down the fork if you decide to attempt it. There are also many past threads on tips and tricks here you can do a search for. There's also YT videos to learn how to do just about anything. Run into a snag, ask.

Usually, refreshing the forks means new fluid, bushings and seals. If just swapping springs, the forks tubes don't need to come apart. Just remove the top cap, remove the spring, pour out the old oil, put the new spring in, set the proper oil level, reinstall the cap. That's simplified, but the basics of it. There are details you need to be aware of but I won't go into them unless you decide to do it.

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2 hours ago, Trailryder42 said:

The forks are just a different animal than the carb that a lot of folks freak about tearing into. Just different, same attention to detail required. If by having the forks "refreshed" you mean bushings and seals too, while the forks are broke down that far, have the shop remove 6 of the shims off the compression stack.

I don't mind doing my forks, but the shock can be finicky to bleed and get right, plus needing the right tools and Nitrogen to recharge it. I've always let the shop do it.

Find a shop manual if you don't have one. The manual gives instruction on how to break down the fork if you decide to attempt it. There are also many past threads on tips and tricks here you can do a search for. There's also YT videos to learn how to do just about anything. Run into a snag, ask.

Usually, refreshing the forks means new fluid, bushings and seals. If just swapping springs, the forks tubes don't need to come apart. Just remove the top cap, remove the spring, pour out the old oil, put the new spring in, set the proper oil level, reinstall the cap. That's simplified, but the basics of it. There are details you need to be aware of but I won't go into them unless you decide to do it.

Were should I run the forks in the triple tree?

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I think most folks recommend running them flush with the top of the top clamp, as I do mine. You get the most hi speed stability like that.

Bleeder 2.jpg

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13 minutes ago, Trailryder42 said:

I think most folks recommend running them flush with the top of the top clamp, as I do mine. You get the most hi speed stability like that.

Bleeder 2.jpg

Thanks. What are your suggestions on front and rear static sag, free sag and rider sag.

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1 hour ago, bluer6 said:

Thanks. What are your suggestions on front and rear static sag, free sag and rider sag.

Set rear rider sag to between 3.5"-4". If spring rate is right, that should give you a free sag(bikes own weight, no rider) of about 1". Depends on the ride you want. I set mine at 4".

The fork rider sag is usually between 35mm-50mm. I wouldn't think with the new springs you need to worry about too much (50mm or more). For reference sake, see what is now with stock springs. I usually put a zip tie around the fork tube while the bike is on a stand. Then carefully take it off the stand and mount the bike. Measure how far the zip tie moved. If a person had to, you'd lessen fork sag by adding a spacer/shim internally between the fork cap and spring.

 

Edited by Trailryder42

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40 minutes ago, Trailryder42 said:

Set rear rider sag to between 3.5"-4". If spring rate is right, that should give you a free sag(bikes own weight, no rider) of about 1". Depends on the ride you want. I set mine at 4".

The fork rider sag is usually between 35mm-50mm. I wouldn't think with the new springs you need to worry about too much (50mm or more). For reference sake, see what is now with stock springs. I usually put a zip tie around the fork tube while the bike is on a stand. Then carefully take it off the stand and mount the bike. Measure how far the zip tie moved. If a person had to, you'd lessen fork sag by adding a spacer/shim internally between the fork cap and spring.

 

Thanks

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My current settings are fork rider sag 63mm fork free sag 44mm. Shock rider sag 106mm shock free sag 47mm.

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I'm right at 200 without gear, and like you, ride trails and enduro type stuff.  No motocross / jumping here.  I'm running a .45 spring in the forks and the stocker on the shock.  With gear on, I set the pre-load in both the forks and the shock to get me to the proper race sag.  Then, looking at the free sag after setting the race sag, the numbers tell me that I'm just a touch on the soft side on both forks and springs.  In my opinion, if the race sag is set properly and the free sag is anywhere in the ballpark, you're good.  In my case, I'm certainly not going to spend tons of money on new springs for a very marginal gain.

In your case, at 170 pounds (i.e. about 30 pounds lighter than me).  I'd go absolutely no more than a .45, probably a .43 on the front.  And keep the stocker in the rear.  Set the preload of both to get the right race sag, and you'll be good to go.

I did the shim stack mod on the forks at the same time as I added the .45 springs, and the combination of those 2 things were, unquestionably, the best mods I've done to the bike yet.  It makes the front end a cloud over smaller bumps, yet hasn't lost any bottoming resistance that I can tell.  Matter of fact, I still haven't bottomed it since I did the shim stack mod and springs nearly a year ago, and that's with the compression clickers on full soft.  If I had to do it again, I might would consider taking 7 shims out instead of 6, simply because I don't see a downside to making it even softer.  

More recently, I rebuilt the shock because of a blown seal, and "revalved" it too.  When I say "revalved", all it really entails is removing a few specific shims from the shim stack.  There are some "how-tos" posted on here from years back that detail which ones to take out.  I've only got a few rides in on it since then, but the results here are extremely similar to the fork.  It is miles better than it was over smaller stuff, yet still nice over bigger hits on the trail.

I run the forks all the way up in the clamps, re:  on the 4th (?) mark from the top.  I do this to help try and lower the bike as much as I can (only about 5' 9" here).  Though I virtually never go faster than 50-60 mph (never need to), I haven't one time felt like the bike was "twitchy" or unstable at those speeds.  And it really does turn awesome like that.

The combination of the fork shim stack mod and re-valved the shock has turned this bike into a fantastically comfortable and easy-to-ride bike in the woods.  It floats right over smaller stuff like it isn't even there, but I can still send it pretty hard over water breaks, log crossings, drop-offs, etc.  The rebound settings are also working well, as the bike really seems to hug the ground no matter how rough the terrain is, and I get excellent grip front and rear.  I am EXTREMELY happy with the suspension on the bike.

Oh, one more thing.  Contrary to what virtually every one of your friends, and almost everyone online will say, rebuilding the shock is NOT hard at all.  Matter of fact, I think it's a good bit easier than the forks.  There's no special tools needed, or anything like that.  The hardest thing is sanding / grinding down the peened-on nut, and if you have a sander or grinder, that takes all of about 1 minute.  If you don't have a grinder, you can buy a very nice Porter Cable one on Amazon for about $35.  Rocky Mountain ATV has a fantastic "how-to" video that walks you through every single step.  When you get it completely finished up, simply take it to your local powersports shop (or suspension shop) and get them to charge it with nitrogen.  This cost me a little over $10.  

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