Oil Options for Stock Forks

[nhchris]

I saw a Dave Moss video in which he recommends 10 weight in general and 15W in a fork leg that controls damping.

I searched the topic here and did not come up with any info.

Have any of you folks experimented with different weight fork oil in stock FJ legs?

If so, what worked for you? (I am 200 lbs w kit and ride sportingly:)

[Heli ATP]

Currently my Niken has was Yamaha calls zero weight oil. For height reduction I had the front springs replaced in the Niken and the kit came with 10 weight oil, which I didn't used. It doesn't ride as good as it had before the spring change and I've been told that if I  replace the stock oil with the 10 weight I will see a huge improvement. So to add to the OPS question, I'm wondering what additional parts should be purchased and replaced for the fork oil change...seals etc?

[betoney]

12 hours ago, nhchris said:

I saw a Dave Moss video in which he recommends 10 weight in general and 15W in a fork leg that controls damping.

That can be a rather misleading recommendation unless you know what brand of oil he is using as viscosity can change between brands for the same viscosity rating. 

Looking at the viscosity chart below, Castrol 10w and Motorex 2.5w both have a viscosity rating of 15.00-15.10 (not all 5w or 10w oils are the same), so if you are going to experiment with different viscosities then stick to one brand for consistency.  

Lighter or heavier viscosity will alter both rebound and compression damping but keep in mind that the early FJ's dont have compression adjustment so you could choose a viscosity that makes the compression react to your liking and then manually adjust the rebound clicker to fine tune.

But yes, to answer your question, choose a brand that you have easy access to (my local shop has Bel Ray and Yamalube and Cyclegear has Motul) and start with 10w, then you could go to either 5w or 15w if you dont like the feel of 10w.

 

[2and3cylinders]

 You're right on the money Bryan and when evaluating the table you provided the index at 40 CST is what is the decider

 Flushing the forks with cheap ATF and draining them Completely

Changing to a straight rate Spring like point 9 or even 95

Air gap is just as important as the viscosity 

And then trial-and-error you can suck out or add without too much difficulty if you know what you're doing Without removing the forks

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[piotrek]

Factory oil is ~15cSt@40C (Yamaha 01 I believe), so if you were happy before... continue using that. If you're not, experiment with a lower value for a more compliant ride, or higher value if you want something firmer. Do this in small increments (say +/- 2) because your compression valve is non-adjustable.

Oil weight selection depends on valving, so what works for me (re-valved) might not be good guidance for you (stock). I am about the same weight, and agree with @2and3cylinders that moving to straight rate springs is a worthy mod while you have the forks apart. I run 0.9 kg/mm. Good luck.

[OZVFR]

Yes, change the springs. 
Stock is only set up for someone that weighs around 125lb, so you’re way of the scale. 
0.95 or even 1kg/mm springs and  heavier oil should do the trick, actually it will transform the bike. Even better if you get it revalved.