Yamaha 01 - 5 wt? - Fork Oil Level on 2000WR - Front fork setup

Alright now I am prepared. I just read every post with "fork oil" in it.

My Specs

170lb rider

ride both trails and MX

US spring .46


My observations

I think the fork is a little mushy for aggressive riding. I drove the bike side by side vs. a stock YZ426 and the WR's dampening seemed too "soft" to control the front end.

Increasing the dampening clickers significantly from stock seemed to help alot. Stock front compression is 7 clicks and I went to 3 which helped alot. I didn't have the opportunity to go in more.

I feel that the fork spring is plenty stiff. This could be part of the reason why I consider the dampening to be weak. Dampening is a funtion of the spring rate. The stiffer the spring the thicker the oil needed to control the spring. The stock US spring shows to be at the stiffer end of things. I have even heard that the "fork tuning pros" go with softer springs for 170lb riders. Confirming that the stock WR is decent for 170lbs.

I am convinced that raising the fork oil level is one step in the right direction.

Goal - I would like to have a suspension setup that works for both trails and MX, and I think the suspension has enough range of adjustment to accomodate this.


Question 1 - Is Yamaha 01 fork oil (stock) really 5wt? There is some debate about this.

Questions 2 - If I only have three more clicks to go in on compression and still think that things could be stiffer, then maybe I should go up to the 7.5wt oil when as raise the fork oil level from a stock 135mm to a 100-105mm setting.

The reason for the question is I see little notice given to anybody going to an thicker oil weight.

Anybody out there use thicker oil?

[This message has been edited by John in Long Beach (edited 07-19-2000).]

i'm no MX guru john, but the idea i thought was that you pushed thin oil through holes & just changed the holes!

when you really work your suspension thick oil goes thin so things deteriate-fast.

if you start with thin oil it can't get thinner so it doesn't deteriate = you keep riding harder for longer.

I have heard Taffy's comment before. As the oil heats up, it gets thinner. Some suspension tuner recommended going with as thin an oil as possible to avoid that. If in fact this does occur, as the moto drags on, your oil gets thinner, and your air spring (air volume in fork) gets hotter. Being directly proportional, heat and pressure, your internal fork pressure increases. Now you have warm oil and higher pressure in your forks. 15 minutes into your moto, as you are getting tired, you are getting beat to death by your forks!

I weigh 170#. Pro Action put in .45# springs in my forks, and re-valved. Pro Action's claim to fame is their 3 stage damping. It is supposed to give you suppleness off the top and increase through the suspension stroke. I do believe my forks are in fact more supple off the top. My OEM forks seemed to resist moving (too much preload?). I still have not hit an MX track to check on the versatility of their vaalve stack. My cost was $300.00.

A heads up: if you send your forks off, pull the rubber plug in the bottom of your forks (compression adjusters). They will be thrown out, at your expense.


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?!!

5wt 130 mm

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