Correct springs for a 250 lb rider 2004 Yamaha WR450F


15 replies to this topic
  • BajaFool

Posted October 12, 2004 - 10:06 AM

#1

I'm helping to setting up the suspension on a new 04 Yamaha WR450F. I estimate that the rider weighs approx. 250 lbs dressed ready to ride. The stock rear spring is rated at 5.20 kg/mm and with the rear suspension set at 100mm of race sag, there is no free sag at all. The stock front fork springs are rated at .46kg/mm and I assume are too soft for the weight of this rider as well. What should the proper spring rates, both front and rear, be for this rider? In case my estimate of 250 lbs for this rider is too heavy, can someone tell me what the weight carrying capacity is of a rear spring that is rated at 5.2 kg/mm and what is the weight that can be accommodated as the spring increases to 5.3 kg/mm, 5.4 kg/mm, etc. and the same for a front spring rated at .46 kg/mm as it is increased to .47 kg/mm, .48 kg/mm, etc. Finally, after the correct springs are installed on the motorcycle, would a knowledgeable person (someone who has been there done that) care to offer compression/rebound settings for an aggressive rider, who usually rides in the Southern California desert. I've been told that the forks, shocks, springs, and linkage are basically the same for the WR400, WR426 and WR450 through the 2004 model year. Spring rates, compression and rebound settings for all of these models should be interchangeable.

  • Top

Posted October 12, 2004 - 11:52 AM

#2

Great question!!!! I look forward to reading some good advice in the near future! :cry:

  • Bluebomber

Posted October 12, 2004 - 01:17 PM

#3

I'm the same size as you. This is one the most important setups you can do for your bike being a big guy. Buy the heavy .49 kg/mm front springs and either a 5.6 or 5.8 rear spring. If you do any kind of motocross you'll need the 5.8 rear spring. I only ride desert and prefer the 5.6. Once you have the springs in you will be able to back off the compression clicker a couple of turns and go up on the rebound clickers. I started with stock setting on the forks and shock. I currently ride the shock with a 5.6 and stock clicker setting. I use 14 compression clicks out and stock rebound clicks on the forks. I hope this helps.

  • Top

Posted October 12, 2004 - 07:06 PM

#4

What do these springs cost, and can a guy do this spring change out at home with home tools, or does a dealer have to do it? Thanks! :cry:

  • Bluebomber

Posted October 13, 2004 - 01:56 PM

#5

Changing out the spring can easy be done at home. There's no special tools needed. Your owners manual has plenty of detail on how to pull the fork springs and rear spring. Rear spring should be about $100 and front springs $110. It is a great mod for a big guys.

  • SXP

Posted October 13, 2004 - 03:12 PM

#6

There is no way in hell you are going to get any free sag with a 5.8 spring (never mind a 5.6 spring) when adjusted for 100 mm of race sag at 250 pounds. I'd recommend a 6.3/6.4 kg/mm spring.

  • chipwich

Posted October 13, 2004 - 07:22 PM

#7

if the average man weighs 165, the rate must be progressive.

i.e. doing a simple ratio

165 250
-- = --
5.2 7.9

determines that all of us fat boys need a 7.9 kg spring :cry:

  • SXP

Posted October 13, 2004 - 07:26 PM

#8

The linkages nix that kind of linear extrapolation :cry:

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  • BajaFool

Posted October 14, 2004 - 12:31 PM

#9

Thanks Bluebomber and SXP for your input. I guess the obvious question is "How can there be such a big difference in recommendations for rear springs for a 250 lb guy who rides in the desert?" The difference between 5.6/5.8 kg. vs 6.3/6.4 kg. is too much to attribute to personnel preference, brands of springs or off the sag specification, just a little high or low. Seems to me that one of these spring recommendations has to be considerably off the mark. Personally, I weigh 210 lbs dressed ready to ride and I ended up with an Eibach 5.4 kg rear spring for desert and Baja trailriding on my 2003 WR450F. Which of you has set your race sag up for between 95-100 mm and ended up with a free sag of 15-25 mm, given that the rider weighs approx. 250 lbs?

  • xcracer123

Posted October 14, 2004 - 04:52 PM

#10

if you go to www.racetech.com you can get free info on correct spring rates for your weight, riding ability, and style of riding you do.

  • Grandville

Posted October 14, 2004 - 05:14 PM

#11

I am 250lb rider with gear. I ride a mix of terrain, in western MD, including rocks, fire trails, hills and tight woods (like the GNCC at Wisp). The below spring sizes work for me. I would also suggest all WR trail rider's try raising the front forks 10mm to 15mm to reduce the bike's top heavy feel and quicken turning response.

  • blireef

Posted October 14, 2004 - 05:17 PM

#12

I've got a 5.6 and 48 on the front and I think I'd go for a 6.0 if I did it over, front seems to be OK. I'm 240+ with gear but never go faster than 25mph. :cry: OK, maybe I do go a little faster than that. :cry: It makes a huge difference where you're going to ride this bike, tight woods?? desert??motocross?? My bike works really good in the woods with my set up but could use some more spring in the desert, and would definately need more springs if I did motocross..Good Luck, I assume you are going to revalve when you change the spring, might as well, it will help a lot. :cry:

  • SXP

Posted October 14, 2004 - 05:41 PM

#13

I'm 225 lbs buck naked and about 250 pounds with my 100 oz Camelback, loaded tool fanny pack, and full protective gear. I bought my WR400 used with a 5.6 kg/mm spring thinking that (based on Race Tech's web site) I'd got a bike with the suspension set up for my weight. NOT. Zero free sag with 100 mm of race sag. All my suspension linkage and bearings are fully lubed and greased. I then picked up a 5.8 kg/mm spring from a TT member. Still no free sag. Bit the bullet and picked up a Race Tech 6.0 spring. Still no free sag. I then saw a TT member selling an Eibach 6.3 spring and grabbed it. Finally, with about 14 mm of preload, I'm in the ball park. Eibach recommends a maximum of 15 mm of preload before going to the next higher rate spring.

I can't expalin the discrepancy between what RT (and other tuners) recommends and what actually worked for me.

My neighbor (same weight as me) on an 03 WR450 runs a 6.0 spring and has zero free sag with 100 mm of race sag.

Check this thread out from the Suspension thread:
http://www.thumperta...5/o/all/fpart/1

Shockdoc is a tuner and a regular contributor to that section.

Good luck.

  • SXP

Posted October 14, 2004 - 05:45 PM

#14

I'd bet you have your spring compressed more than 15 mm (preload) and have ZERO free sag.

  • BajaFool

Posted October 14, 2004 - 09:55 PM

#15

Here is our plan. We are going to swap springs with a guy who bought a used WR400 that is way over sprung for his weight. We had his springs tested today and they are .49 kg/mm front springs and 6.0 kg/mm rear shock springs. This guy is in the 160 lb range ready to ride----- so, he will be very happy with the stock springs from my son's 2004 WR450. The .49 kg/mm front springs are as stiff as you can buy and the 6.0 kg/mm rear spring is much closer to being the correct spring than the stock 5.2.kg/mm spring. I want to believe that this is going to work. If it doesn't work then all I can say is, "We were going to have to buy new springs anyway, because staying with the stock springs was not an option".

  • Chevy_Cowboy

Posted October 14, 2004 - 10:11 PM

#16

Here is our plan. We are going to swap springs with a guy who bought a used WR400 that is way over sprung for his weight. We had his springs tested today and they are .49 kg/mm front springs and 6.0 kg/mm rear shock springs. This guy is in the 160 lb range ready to ride----- so, he will be very happy with the stock springs from my son's 2004 WR450. The .49 kg/mm front springs are as stiff as you can buy and the 6.0 kg/mm rear spring is much closer to being the correct spring than the stock 5.2.kg/mm spring. I want to believe that this is going to work. If it doesn't work then all I can say is, "We were going to have to buy new springs anyway, because staying with the stock springs was not an option".


I'd say your setup will work fine for your son... but I just wanted to let you know .49 isn't the stiffest fork springs you can buy... MX-Tech has WR fork springs up to .52 :cry:




 
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