springs for 2004 wr450f with a heavy slow guy

Hey guys,

I have owned my first dirtbike for just about a year now, a 2004 wr450f. Been having a blast doing enduros and hare scrambles.

I'm 230lb naked on my bathroom scale in the morning, and a mid-pack C rider. From all i've read, the springs could use a higher rate to support me. I don't think I'm at the ability level yet where I need to send off the suspension for an entire revalve too, but would like to improve upon it some if adding stiffer springs for my weight will help.

what rates do you guys think I should go with?

stock (according to racetech's site) fork springs are .46kg/mm - their calculator says i should use a .51kg/mm - the highest they carry is a .48kg/mm however? Who else carries quality fork springs in the recommended rate for my size? is .51kg/mm excessive?

stock rear spring is 5.3kg/mm - racetech's calculator recommends 5.8kg/mm for my riding and weight. Does this seem reasonable?



I am a slow C rider and weigh about the same as you. My 07 suspension was revalved for a lighter A rider before I bought it, I just changed the springs.

Forks - I run a .48. It came with a .49 and the suspension guy said I was not using all the action, so I went down one. It is still a little stiff but I think it is the valving. The forks still deflect off of rocks and can be dangerous, they put me in the hospital for a week with broken ribs. See what Krannie is doing with his WR to try to correct the issues.

Shock. It came with a 5.8 and I went up to a 6.2 to get the sag right. A little too stiff yet like the forks.

As I get faster the setup works better. I rode it on an MX track and it worked well, maybe would like to go back to the .49 in the forks if I was jumping a lot. Would change out the stock forks for the newer SSS forks if I had the money. Might still do it.

I'm in a similar (But unfortunately heavier.) boat. However thus far I'm not bottoming out at all so I'm sticking with what I've got for now however I'm going to watch this thread with interest. I'm sure as I get faster/better that will change so I'll need to do something.

I'm an older guy, 65 and go 230#, I don't know how to classify my ability, I can still go pretty good through the single track, but own both an 07 WR 250 and an 05 WR450, I've installed heavier than stock fork springs in both, as much to keep the front from diving as anything. I had difficulty particularly with the 250 in deep sand and this made a remarkable difference, went up on the rear on the 250 as well, but haven't found it necessary to switch the rear out on the 450. You may be able to relax the compression settings with the heavier spring enough so that it doesn't deflect as much. Good Luck.

So anyone know where to get Heavy Fork Springs for these Forks? Racetech still the only place? like the original posted stated they don't list anything heavy

So anyone know where to get Heavy Fork Springs for these Forks? Racetech still the only place? like the original posted stated they don't list anything heavy

Race tech has heavier springs for sure. Just call them.

or http://www.mx-tech.com/

I'm about the same as you in terms of speed, and I weigh 210lbs

I run 6.0kg in the rear and 0.46kg/mm up front (0.44 were too soft). Rear sag figures are 28 / 103mm which ain't far off, so I'd say you need at least a 6 in the rear

Front springs are notorious for being soft - they are supposed to 0.44 as the come from Yamaha, but mine were measured at 0.41 so had to upgrade just to put it back where it was supposed to be

0.51 fork springs will be too hard - this is supermoto territory not dirt track

(stock spring rates refer to my 08 model)

Edited by GuyGraham

As GuyGraham said, the stockers might "claim" to be one weight range, but measure completely softer in actuallity. I understand you not wanting to throw to much money into the suspension if you don't have too, but it's probably the smartest thing to do.

If you increase the spring rate drastically from stock, the spring is able to store more energy in it (this is what springs do), and then the valving has to be able to dampen that extra energy. This is one of the weakest parts of the WR's suspension designs, as I've found that the rebound capability is weak, stock.

Money spent on suspension is probably the best money spent on a bike. You can look into doing it yourself, with a kit like Smart Performance. It seems like there is a ton of people on ThumperTalk that have tried it, and rave about it.

You might want to post something over in the Suspension Forum too, and see what they have to say.


i ended up, after re-springing my suspension on my own and it being absolutely awful, sending it all to factory connection for the whole service...

they actually traded out the springs i had just bought from them for different ones....WAY different that what race-tech's calculator called for. and it turned out so so so much better....

i put in .49kg fork springs and they were stiff....didn't have much rider sag at all. it was obvious to me when riding the bike they were too stiff as i couldn't dream of using all the travel. race tech's calculator (as you can see from my original post to start this thread) suggested EVEN STIFFER SPRINGS! screw that!

factory connection installed .47kg fork springs on my 04 wr, and now all is well with my sag numbers (read, where they should be). they also traded out the 6.0kg rear spring i put on for a stiffer 6.3kg rear spring.

my bike has never ridden as smooth or as controlled. it is amazing. something about the geometry of these older wr's must not require the fork springs to be as heavy - or more of the weight is carried on the rear wheel. because i can tell you, i am 250 lb, and .49kg fork springs were too stiff by a good margin.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now