Fork Oil

I've got a stock 04 450.

I want to add some fork oil to help resist bottoming.

Can I just add some Bel-Ray 5wt or do I have to get the Yamaha 01 stock suspension fluid?

Are the two oils compatible?

Also, I had a leaky fork seal that was caused by some dirt in the seal.

I got it fixed with the film negative trick.

Is there any easy way to measure the fork oil volume/height without fork disassembly? I think I lost a little bit of oil due to the leaky seal.


The "01" spec in the manual is, according to both dealers I checked with originally, 5wt fork oil. Bel-Ray is probably compatible.

One problem with adding oil this way is that you may not know: a) what the current oil level is, and/or :cry: how much oil it takes to raise the level a certain amount.

If you exceed the maximum oil height, you won't like the results, so at least, pull the springs, set the bike on the ground, and measure and adjust the oil level accurately. Ideally, you should drain and refill. It's probably time to do that anyway.

You will be much happier if you follow gratracer's advice.

Start with fresh oil and an oil level that YOU know you set. Then you can experiment with adding or subtracting oil.

i was under the impression that yamaha 01 fork oil is the equivelant to 0 weight. :cry: i could be wrong.

That's not what I was told, as I said, by two different service departments (not parts guys). It gets even more confusing than that sometimes. When I asked for the "01" oil that the manual called for, I was handed a bottle of Maxima Fork Fluid "85-150" !! Further down the label, it says "5 Wt"

o1 is 5 wt oil. open up your forks and drain your old oil and put new oil in at the proper height. Get a fork oil height tool ($30). It is worth it. It works like a giant syringe with a depth controlled "needle". Very accurate for setting oil height.

I like the Honda standard fork oil. It seems to work better (higher quality stuff).

beezer is right. Many rebuild shops like to use the Honda SS oil. It is a high quality fork oil.

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