standard fork/shock spring rates?

4 replies to this topic
  • Kevin_in_New_Hampshire

Posted July 08, 2000 - 04:44 PM


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?!!

  • Matt_Porritt

Posted July 08, 2000 - 10:45 PM


For 99 YZ400F

Fork 0.46kg (Europe 0.45 Progressive springs)
Shock 5.4kg (Europe 5.4 Progressive Spring)

**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
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  • Guest_Guest_*

Posted July 10, 2000 - 03:19 AM


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

  • Taffy

Posted July 10, 2000 - 10:14 AM


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?

  • DaveJ

Posted July 11, 2000 - 11:14 AM


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.

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