XR4 Suspension

CPT Jack

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#1
Well my team Knucklehead cohort, the Eel, finally squared me away this weekend and helped me out by setting the sag on my bike (I had heard of this "sag" thing once or twice before). We rode whoops for a couple hours, adjusting the clickers & experimenting. My bars were also pretty low, so we adjusted those up. Huge difference. It's so much easier to steer & the whoops aren't as scary as they used to be. We took on the nasty forest trails at Gorman once again & started up the mountain. These were challenging and the front end was everywhere - bouncing off both sides of the singletrack. We softened the compression 2 clicks, but we were pretty much on top so I'm not sure of the adjustment in terms of "uphill feel". Going downhill was amazing though. The front end tracked thru everything & really inspired confidence.:cool: I was able to go much faster than ever before and still felt in control. I remember thinking to myself "This is easy ... I can't believe I'm going this fast ... this used to freak me out!"

So now that I'm getting into suspension & handling, I have a few related questions for those in the know.

Is there some kind of baseline setting for the front end, like a front sag?

How can I tell if I have the right springs for my weight? I'm 200-205

How are the stock forks on a 98 XR400?

I've seen fork for sale on ebay (like 99CR250 forks) than probably cost the same as a revalve/respring. Would they fit on my bike and would they be a big improvement?

Thanks in advance for your help and recommendations!
 
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#2
CPT Jack.

IMO, for the type of riding you do, the XR forks are pretty good. The way I check for balanced sag is to stand on the pegs in your normal riding position and bounce up and down. Both ends should move about the same amount. If the back end moves up and down 8" and the front end only moves about 4" then, you may want a little more sag in the front end. Both ends should move about the same amount. The suspension guru's here may have other ways to do this, but, this has worked for me.

I would stay away from the CR forks because they are upside down forks designed for moto cross and would be too harsh on trail. The amount of money spent to soften them up for trail use would be better spent on your stock forks.

Most of the time for trail riding, your forks can be dialed in by using different fork oil weights or by adjusting your clickers.

If you and Eel are coming out to the Big Bear ride, there will be plenty of people there that can check out your suspension for you.

Just my $ .02 only worth about 1/10 of a cent here in Kalifornia.:scream:

Ol'89r
 
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#3
XR4 Boingers OK 4U

Originally posted by CPT Jack
Is there some kind of baseline setting for the front end, like a front sag?
Go to the Race Tech site, http://4.22.116.247:81/cgi-win/racetechv2.exe

It say U need 15mm preload, but B 4warned: that's w/all of their other recommendations in place.

>How can I tell if I have the right springs for my weight? I'm 200-205

Your fork springs R waaaayyyy off. They recommend 0.46kg/mm 4U. R yours stock or did the prev. owner(s) change them out? Either way, the .46s R 4U.

The stock shock spring is right on.

>How are the stock forks on a 98 XR400?

Just fine 4 your type of riding, moreso once dialed-in.

>I've seen fork for sale on ebay (like 99CR250 forks) than probably cost the same as a revalve/respring. Would they fit on my bike and would they be a big improvement?

They would fit w/a moderate amount of work & $$, would perform much better (after revalving/respringing 4 this retrofit), but not unless you've reached the limits of the stock forks.

I did just that to a DR350 (sim to an XR4), where I put an entire RMX front end & rear shock on. $1k later it was two or three notches better than the revalved/sprung stock suspension. I've heard of a few who have done it to an XR4.

I do not recommend this route as it becomes expensive fast, moreover the XR (DR, etc.) frames R not gusseted/strengthened/designed to take the stress/loads of USD forks. Eg: the guy who bought it from me broke the steering stem in no time; it may be his habit to MX & leap it, & he weighed 50 lbs more than me. I do not know how the frame held up in all this.

I do recommend having a shop service & revalve both ends (@ a minimum, springs on front - U can do that, & cahnge the oil/set the level). Baja Des., RT, & Scott's have XR experience, or better yet, Jeremy. Yes, it's expensive, but well worth it - best $ to spend on your XR by far.
 

CPT Jack

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#6
Boingers ... that's funny!

That's gonna be my new word of the day!
P-last, I'm not sure what either of the previous owners did, so I don't know what size springs I'm running ...:( . I should probably order the spring & have & the work done if I'm that far off from stock.

Wolf, all that work sounds cool to have done, but how much of a difference will it make and how do you rate your suspension overall?

Thx for the input!
 
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#8
Re: Boingers ... that's funny!

Originally posted by CPT Jack
I'm not sure what either of the previous owners did, so I don't know what size springs I'm running ...:( . I should probably order the spring & have & the work done if I'm that far off from stock.
Good suspension shops have a tool 4 checking shock springs rates; don't know if there's such a thing for or how they test fork springs. @ ~$80 a pair, it's certainly worth a phone call or 3.

Ask Eel-er if his brace made a $200 diff. or not here in SoCal conditions (I cannot remember what his conclusion was, but I do not see many XR owners around here w/them) - it certainly wouldn't hurt, but I believe starting w/improving the fork action is your immediate concern/best spent $.
 
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#9
I am with the XR Wolf ,spend the $ 200 on the SRC fork brace it is worth EVERY PENNY.Then revalve as finances permit.If you ride out west style a stabilizer really helps(Scotts,GRP etc..):cool:
 
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#10
Hello,
I'm considering doing some work on my XR4. I'm torn by what to do first. I want a Mikuni pumper, I would also like to balance my stock suspension by putting in new springs on the fork and tweaking the fork oil. I've also considered the Scotts fork brace, if it will help in the soft sand conditions I ride in. I know squat about suspension though. I should ship off my forks and shock for a full blown revalve etc., unfortunately, I can't see myself doing that, or spending that kind of money.

What do you people recommend? Rear shock is about right for me, 190lbs without gear, but I know the front springs could be beefed up. What tools and knowledge is needed to put in new springs, seals etc. and do it PROPERLY?? What about the fork brace? What terrain does it work best?? Any recommendations are welcome. Any constructive criticism on the Mikuni pumper, or is it the best thing since sliced bread? Thanks in advance.
 
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#11
I just installed an SRC fork brace this last week on my "00XR4. Only been for one 15 mile ride so far but indications are, I think I'm gonna like this thing. The only other thing I've done to my stock forks is change the oil to Mobile 1 ATF and that was a few weeks ago. The forks seem to soak up the rocks much better now and control on rocky, loose downhills seem to be better. Have yet to ride with it in sand and whoops but I expect control to be better there too. I was gonna put in heavier springs but now think I'll wait and evaluate the brace a while before I make any decision to respring. Seems to be a good mod and worth the money. I also bought the optional fork skins.
 
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#12
Hey,
Thanks for the reply. In the terrain I ride in, the suspension works decent enough. My biggest problem is the front wants to wash out in sandy turns and when following a two track groove in the sand. I've learned to compensate. Keeping on the gas hard lightens the front, but I still have to weight the rear to keep the front from swimming. I attribute this to not just the sand, but the fact that my rear spring is good for my weight but the fork springs are soft, therefore, not balanced.