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Should I go by Fredette's or Race Tech's spring rates? I weigh 150-155 lbs in my birthday suit, and probably somewhere around 170 with gear.



Fredette recommends:

Forks-.38 kg SPRING for riders that weigh between 140-190 lbs. A big range.

Shock- 4.8 kg SPRING for riders weighing between 150-180 lbs.
I assume his recommendations are based on a rider+gear weight.



Race Tech recommends:

Forks- .405 kg spring. They state to "use closest available", which is a .42 kg spring. This is a big difference from stock.

Shock- 5.009 kg spring. This is basically stock.



The forks are going to be the biggest improvement obviously, but is the stock shock close enough for my weight? I read on another thread that Fredette's recommendations are geared more towards racing, and they are a little light.
Thanks

When I had my forks built, he put .41 springs in it.....they are/where just right for 160# rider. Mine are set up for "slow "B" dessert/woods rider (I am unfortunately not a slow B rider, more like a Slow C). Given that, I think that Race Tech's calculator is a better choice to use.

I personally would go with Race Tech's recommendation. I went with theirs and it has worked out good for me. They recommended for me (150lb B-rider) a .42/4.8 setup. I already had .41 fork springs and replaced the stock 4.7 up to a new 4.8.

If racetech recommends 0.405, then the closest would be 0.40 no? If they recommended 0.415 then the closest would be 0.42. I've just ordered a set of 0.44 for USD forks and I weigh 180-185 without any gear. Going to keep the stock shock for now and see how the bike handles. Should arrive anytime now.

Did you check the sag with the stock spring?

Are you asking me or throttleout?

Bitteenit, Race Tech doesn't show any springs under the .42 kg. But, otherwise you're right.

Jason, I haven't set the sag yet. But, I see where you're going. I need to let the sag determine my shock spring rate...correct? I'm going to set my sag now, and then check it again when I replace my fork springs.

Since Race Tech doesn't offer a spring less than .42 I was looking at getting FRP's springs. FRP fork springs start at .38 and go to .42 kg.

I went back to playing with RT's calculator. Those original RT recommendations were based off of a B rider. I've never raced and don't know where I would land on that scale. I changed the rider level to c class, and now it recommends the same fork spring as FRP- .38 kg but the still the stock shock spring. I don't understand how riding level affects the spring rate. ???

I've wondered that too. I suppose a more aggressive rider will want to go faster and as such want stiffer springs. I'm by no means a racer myself, and I think spring rates would also vary a lot according to the type of terrain you ride in and what you're accustomed to. Once I get the 0.44s on I'll report back. Kind of worried they might be slightly stiff but it should be fine. I haven't put many hours on the stock springs but can tell they're way too soft, so anything will likely make it more comfortable (and I can also let my 220-240lbs friends ride it... Though I'm not sure that's an entirely good thing as they might want to "borrow" it too often).

I'm about the same weight and found that the stiffer of the XR400 springs was perfect for me.

I think they are .42 from the 97+ XR400? The nice thing about the XR springs is that you don't use that 5" steel spacer, instead you make a spacer about 5/8" long out of a PVC pipe fitting.

The rear shock rate turned out fine for me at 175 and my riding style.

You may be fine with the stock shock spring. I can't see .38 being correct.

KarlP, 1996 / 1997 is .40 and 1998 - 2004 are .40 on the XR400R springs.

Thanks for all the input. I can't find any XR springs, and neither Race Tech nor Eibach offer a spring less than .42 kg. So, I'm gonna go with FRP's .40 kg fork springs. I have to assume his springs are quality. Surely they're manufactured by Race Tech or someone else big.

I don't know your riding experience, BUT, being a touch stiff on the front is not a bad thing. as you begin to get better you'll appreciate it. At least I did/do.

I'm about 180 with gear, racetech recommended .44 fork springs, that's what I went with and think they're just right. Glad I didn't go softer.

If you want .40 springs, here you go:

http://www.ronayers.com/Search.aspx?k=51401-KCY-761

buy 2

Bringing this thread back for fork set up advice. I was installing xr400 .40 springs, and had planned on doing the shim stack mod. To my pleasant surprise I have gold valves. The springs are engraved with .38 or .35 or something. Not very legible. Take a look and see what you think they may be.
Are these the stock .35's? Anyways, knowing I have gold valves threw a wrench in my plan. What weight oil should I use with which springs now?

What length does my pre load spacer need to be for the xr springs??????
Thanks,

I went ahead and installed the XR400 springs with a 7mm spacer. That was recommended to another very similar rider and setup on this site. I used a 50/50 mix to make 7.5wt oil. Got it done. I'm riding tomorrow at West Point, Tn. If I can tell a difference I'll give a ride report.