Jump to content
Sign in to follow this  

standard fork/shock spring rates?

Recommended Posts

Any of you guys know the standard spring rates for the 99 YZF??

Also, anyone know of the recommended spring rates the MX mags dish out for the '99 (you know, "We'd go up to a X spring rate on the fork/shock to balance out the bike"). Pro Action put 45's in my forks w/ the standard rear spring (50??). I think the bike is out of balance now.


99 WR, all YZ mods, de-octopused, OEM YZ tank and IMS seat, jetting by Clark, got forked by Pro Action.


For clarification: WE'LL be having a KICK ASS time in Moab!! Right Mitch?!!

Share this post

Link to post
Share on other sites

The manual says the stock spring rates are whatever Matt said and for a 165 lb rider, but I talked to race tech and they said the stock rates were for a 200 lb rider. I can't believe this. This is directly off their web page for a 200 lb rider. They say to go lighter than stock for a 200 lb rider.

Sorry about the formatting



Model Yamaha 1999 YZ 400F

Date Monday, July 10, 2000

Custom Setup Serial Number 200007105946.68

Rider Weight without gear 200 lbs

Type Riding Motocross

Skill Level Intermediate / Amateur

Age Group Standard Age - Up to 39

Height Standard Height

Stiffness Preference Standard Stiffness


Oil (US-1 = 5w US-2 = 10w US-3 = 15w) US-1

Oil Level 95 mm

Compression Adjuster (Out – counterclockwise) 12

Rebound Adjuster (Out – counterclockwise) 12

Recommended Fork Spring Rate (use closest available) 0.457 kg/mm

Stock Fork Spring Rate (measured) .465 kg/mm (stock)

Recommended Fork Spring Preload 8 mm


Shock Valving Comments Standard Installation

Oil US-1

Nitrogen Pressure (14.5 psi =1 bar) 175 psi

Compression Adjuster (Out – counterclockwise) 15

High Speed Compression Adjuster (Out – counterclockwise) n/a

Rebound Adjuster (Out – counterclockwise) 12

Recommended Shock Spring Rate (use closest available) 5.320 kg/mm

Stock Shock Spring Rate (measured) 5.5 kg/mm (stock)

Recommended Shock Spring Preload 14 mm

Rear End Sag 95 mm

Share this post

Link to post
Share on other sites

i own the WR400 (99) & weigh 200LB. i've just had the gold valve treatment .46 springs front & thought they were good first time out. the rear spring is a 5.5kg & at the moment is set at 26mm preload due to the rear shock wanting a re-valve.

this set up is good for me but i wouldn't want to weigh 165lb & have a bike thats 20lb lighter as well.

i did a hare & hounds yesterday & even with the fork compression valves right off the front wheel was being thrown about on small bumps.

the bike was far easier to ride than the old .42 springs for my weight. now i've got to get used to the hit coming up the legs.

anybody know how to soften the initial travel?

Share this post

Link to post
Share on other sites

I went with the Race Tech gold valve route. I think in speaking with their techs we concluded on the .46 spring for my 160 lbs (without gear). The valve stack, mostly high compression, was the biggest issue with ride quality (ie, it sucked!). With mid-valve removed, and both low and high stacks modified, life is much MUCH better. In other words, what I thought was a spring problem was a valve problem.

However, I still think that I could go with a slightly softer spring for the fun trail riding, then perhaps the .46 for the motocross stuff.

And by the way, I started with Lindermann (LE) on the forks. It was better than factory, but lacked the ride quality and flexibility for change (adjustability) that I got with Race Tech.

Hope that helps.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

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

Reply with:

Sign in to follow this  

  • Similar Content

    • By BDTRENT
      Selling an FMF Power Core 4 exhaust system off my 450FX. Exhaust has 80 hours and is 100% functional. This will also fit the 14-15 YZ450F and 16-18 Wr450F. If needed I can also include new muffler packing although it does not need it. 
    • By Woody Oakson
      I have a 2008 YZ450F with a stock header pipe and Pro Circuit T-4 Slip-On Exhaust. I'm 99% sure the slip on is shot because its loud as hell and when I take it off and shake it it rattles. I would repack it but the screws are all stripped ect.
      Anyways I've gone over the carb multiple times and I've got it running pretty well. The only issue I have with the bike is that it sputters and pops around 1/2 throttle when I hold it there. When I give it full throttle from any RPM it runs great or when I give it about 3/4 throttle it spins up like a top to redline.
      Initially the popping and sputtering was way worse I made the situation better by moving the pilot jet up in a few sizes from a 45 (stock) to a 62. The issue has gotten way better since then but I'm not super sure what to do from here. Should I keep moving my pilot jet up in size because that's a pretty large jump right? I tried changing my needle clip position but that didn't help much if anything it just made starting it worse and little to no impact on the ride.
      Any input on this would be helpful. I don't want to buy other slip on. Also as for the rest of the carb I'm very sure everything else in it is what it needs to be at. I've replaced all the gaskets and O-rings cleaned all the jets, valve holes ect. fixed the accelerator pump timing. I just thinks its strange that my pilot jet size is going so far from the stock 45, but all symptoms point to the bike running lean.
    • By Haydenbaha
      Hi I was wondering if y’all have been using a 450 on your YZ250F?
    • By RockerYZWR
      Excel Takasago 17x3 front and 17x5 rear supermoto wheels with Metzler M3 tires in very lightly used condition. Less than 200 miles total on the setup. Warp 9 spokes. Rear has a Talon hub with 45T Sunstar steel sprocket and OEM rear disc, and front has a polished OEM Yamaha WR450F hub (for the stock speedometer), with a Motomaster 320mm disc. Included is a DID gold o-ring chain, 14T front sprocket, and front brake caliper adapter for a truly turn key setup. Everything is in excellent condition, not a single scratch on these wheels. Came off my '11 WR450F, but will fit many different Yamahas with 20mm front and 22mm rear axles. Asking $1400 plus shipping.
      **Will be driving up near Atlanta, then to northern Louisiana, OKC, and down through Dallas and Houston, TX soon -- can meet or deliver if in the area (Aug 31-Sep 9)**
    • By YZ426fNC
      Hi I’m new on the forum and I was wondering if a 2001 Yamaha YZ426f clutch is interchangeable with a 2002 Yamaha YZ426f clutch thanks , Coleman