What's the WR426 fork spring rate?

6 replies to this topic
  • pablo83

Posted October 19, 2009 - 09:14 AM


What's the WR426 stock fork spring rate?

The manual says it's 4.51, so does the microfiche. But the fiche also says the YZ has a stock spring rate of 4.51 but the YZ feels much much stiffer. Anyone?

I did a search and did not find the answer.

  • matt4x4

Posted October 20, 2009 - 05:05 AM


all I ever found on BOTH bikes was 4.51 is stock for the spring rate, I believe the difference you feel is in the valving and the total weight of the bike+rider - remember that the WR is a much heavier bike - esp. with a full tank, so a heavier spring (4.8) would probably make the WR feel a little more like the YZ.

Edited by matt4x4, October 20, 2009 - 07:21 AM.

  • bakeyz426f

Posted October 20, 2009 - 05:01 PM


i put yz426f forks and a rear shock on my wr426f and it is much stiffer. pretty big difference.

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  • matt4x4

Posted October 21, 2009 - 05:51 AM


but the springs will be one and the same if they were stock - it's all in the valves I believe.

  • pablo83

Posted October 21, 2009 - 09:34 AM


i put yz426f forks and a rear shock on my wr426f and it is much stiffer. pretty big difference.

exactly, and I've put YZ fork valving in my WR and felt very little difference. I have a hard time believing the YZ and WR have the same springs. I think the WR comes with something like 3.82 fork springs, but my springs aren't marked so I don't know. Anyone?

  • matt4x4

Posted October 22, 2009 - 09:03 AM


hmm - looking at the 2000/01/02 WR400/426 vs the YZ426 - we have (look under front forks in microfiche to get stock part number):

Part 18/38 - the WR has a (K=4.51N/mm) rating (multiply that by 0.101968 to get kg/mm) = 0.4987kg/mm - so say K=0.46

Part 19/39 - the YZ has a (K=0.46) rating

I'm not sure why they give the ratings in Newtons for one and KG for the other - seems like they corrected it in 2003.

Looking at the 2003 model:
both bikes have the spring listed in N/mm and both have the 4.51 stock rating given
the o4 model also lists both at 4.51 (wr) and 4.5 (YZ)

If you read your manual, it also shows what your stock spring rate is for the bike - 0.46 kg/mm for the WR. Not sure where you are getting your 3.82 or .39kg/mm from....

The dry weight difference between the two bikes is supposedly about 20 pounds, then add the extra coolant in the reservoir as well as a full tank (almost twice as big as the YZ tank) and you're likely up around 30+lbs more for the WR - go figure it would be a lot softer feeling.......try riding a YZ426F at 180 lbs and then strapping another 30lbs to yourself and riding it again - it's going to feel WAY different.

I'll be replacing my stock fork springs on my bike this winter so I'll get the code and cross reference it back at that time but I have to get the jobs on the bench out of the way first so it'll be a few months before I get to it.

If you go to race tech and see what's stock, they also say 4.51, and their recommendation is 4.6, but using their calculator - unless you're 170-180 lbs you won't get anything under 4.7 as a recommendation for the WR - my weight of 187 and a full tank wants me to use a 4.74 spring so I'm planning on a 4.8 upgrade for mine.

Edited by matt4x4, October 22, 2009 - 09:50 AM.

  • pablo83

Posted October 24, 2009 - 03:21 PM


I pulled the fork spring and put it on my press. It took 24 lbs to push it 1 inch. Who's good at math here? How do I convert that to N/MM?

[EDIT] I found a conversion calculator, so my fork spring rate is 4.20 N/mm. That makes more since than 4.51. In my manual this is listed as the stock spring for Europe.


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