Fork oil weight

[pencilbeam]

What fork oil weight should I use in normal temperatures like California?
(Not Finland :laugh: ) And how to measure the correct amount in each leg? Cleaned and replaced seals and dust cover and ready to finish the job. Thanks!

[Skins]

The factory recommendation is SAE10, which should be suitable for California.

[Finnpaso]

Hey, Pencilbeam, also in Finland NORMAL temperature, what is surely liitle lower, that in land of "hope and glory :laugh: :laugh: :laugh:" , but to topic, in 750 Paso, its mentioned that 350cc in both fork, but in 907IE it was something, like 180mm from top(if i am remembering right). Those can bo found from workshop manuals. Surely U have one We use here 5W, so that 10W can be good to You, i think

[pencilbeam]

Thanks very much! The only thing normal about California is the temp. :laugh:

[Rogero]

You can't smoke anywhere in that state

[Finnpaso]

..... & i have heard, that there are very tight rules about loud motorbikes, hard emission rules, etc..... :laugh: Can anyone confirm that?

[pencilbeam]

..... & i have heard, that there are very tight rules about loud motorbikes, hard emission rules, etc..... :laugh: Can anyone confirm that?

With all the Harleys here, loud isn't a problem and nobody checks to make sure you have all the emissions stuff. I have some friends from Germany who told me they will take your bike away if it doesn't have all the right stuff....

[Marinus]

I have been talking with a guy who races Ducati,s and he said he will play aground between 5w and 20w sometime even heaver. It is a feeling thing in your climate. The thicker the oil the harder the ride. I am just about to change the oil in mine and will start at 10w. 700ml of oil doesn’t cost that much and if it’s not too big a mission to change I’ll try a few different viscosities. With the limited preload and damping adjustment oil W is going to make the biggest difference to your front end handling. A racing friend of mine said for good balance he tries to get the front and the back rising and falling at the same rate when bouncing on the seat at rest and the rebound in both should be controlled and with out a sudden stop at the top. How hard is a personal preference. But if you jump up and down in the center point of the bike and one end moves and the other doesn’t (like mine when I started) chances are there is some room to improve your handing. Remember Comfortable and fast are not always the same but balance is balance.

Hay Antti I am surprised to hear you running 5w I guess all that up and down movement doesn’t get you to hot. Must only work in winter.:funny: :funny:

[pencilbeam]

Thanks for the info Marinus, I actually have 15w in it right now and it seems to have a low speed headshake it never had before, since everything else is the same I'm wondering if I should go to 10w. The other thing I'm curious about is since the shop manual doesn't give a volume measurement for the fork oil but a fill level measurement, do both fork legs actually take 350ml or is the right leg different becuase of the damping adjustment?

[Marinus]

Although both forks a different it dose say 350ml in each. As for the low speed headshake Mine has that too even with a brand new and balanced tire. Is there any thing else you had loose during the operation?

[pencilbeam]

Although both forks a different it dose say 350ml in each. As for the low speed headshake Mine has that too even with a brand new and balanced tire. Is there any thing else you had loose during the operation?

My front tyre was down to about 25 psi so I put it back to the usual 36 and will try it again. The only other thing could be that the forks are slightly out of alignment. So I will loosen the axle and all the fork clamps slightly and push the front end down. Possibly do a slow speed ride around the block. Then tighten everything back up and cross my fingers. The only time mine shakes is when I'm coasting with hands mostly off the bars. Never did that before.

[Finnpaso]

Marinus, i have about 10 very close Ducati friends here in this part of Finland and some have raced lot with 888 in earlier years and they have plenty of knowinig about fron forks. 90% of them drive currently with 5W oil, and temps are hear about 20...28C at summertime. Same with jap bikes also.... I dont know those farenheits at all, so sorry for that... I think they belong to U.K, or ... somewhere... :laugh: I have heard, that they drive in U.K different side of roads, than in other world... :laugh:

[Marinus]

All I know about Fahrenheit is that when its – 40c it’s also -40f and either way its fxxxxx cold. I live in a place where it never goes under zero c. We’ll leave the Fahrenheit to the Americans and they drive on the same side of the road as you. A lot of the roads I ride my bike on have no lines in the middle and little other traffic so I can pick my own side .
Hard or soft, thick or thin it’s all personal preference. I’m sure everyone has there own idea about what feels best :laugh: .

[jomo]

If you have low speed head-shake, it is most likely your Michelin front tyre is 70% worn or better. Solution...change to Bridgestone Battleaxe 130/70-16......end of problem.

If you have head-shake in corners at speed, check tyre pressures first.....minimum 31PSI or 220kpa. 36PSI 250KPA rear.

If still not right.... replace fork oil to specification. In Australia it is called Automatic Transmission Fluid (ATF)

If still not right.... Adjust rebound setting on fork leg- try one click harder than standard.

This is my opinion only, but nothing will keep with the 906 when the road gets rough! That is when you know your suspension is right!!!

[Marinus]

This comes from http://www.strappe.com/suspension.html

There is more info there so take a look. knowing what the reason for the air is helps. So now you know it's not about haw much oil is in each fork but how much air is each fork.

Oil level:
The fork oil's primary function is to be pushed through small holes to damp the rebound of the spring. In an automotive shock, this is the only function of the oil.

However, in a bike fork there is the spring, the oil, and the trapped air above the oil.

This air is important - air, when compressed, acts like a spring, but with a rising rate. That is, the more it's compressed the more force it takes to compress it a bit more. Most fork springs, on the other hand, are linear (straight rate).

The idea is to set the oil level so that the right amount of air is trapped to keep the forks from solid metal contact at full compression. (Obviously, bottoming the fork internals leads to a harsh ride and component damage.) The right amount of oil will allow nearly all of the fork travel to be used in riding and stopping.

How do you find out what's needed?

First, with the cap and spring out of the fork, find out what the maximum travel is (when the fork internals bottom out) {Ihave not done this but the paso book said 140mm}. Then reassemble the forks and install the recommended amount of oil.

Second, once the forks are on the bike, take a zip tie (plastic cable tie) and put it around the fork tube above the slider - make it tight enough that it'll stay where it's pushed by the slider's dust cap.

Third, go for a ride. Do some hard stops with the front brake. Do stoppies if you can.

Fourth, back in the shop, compare the position of the zip tie with the previously measured maximum travel. I like to get the working travel to within 1/4 inch of maximum.

If the working travel is too little, remove a bit of oil.

If it's near or equal to the max, add some.

The best way to do this is to remove the fork springs (support the front end first) and measure the oil level in each leg with the forks totally compressed.

Measure the distance from the top of the tube to the oil level. If you want to make changes, I'd suggest a level change of no more than 10mm at a time.

It's hopeless to try to measure oil volume accurately once it's in the forks, that's why we measure level instead.

Here's an example:

Take a look at my SV650's log - you'll see in column 7 I set the oil level at 124mm, which yielded a total travel of 112mm, 10mm short of the target of 122mm. In column 8 I reduced it to 127mm, for a total travel of 115mm. In column 9, I dropped it further to 132mm, which produced travel of 122mm. Right on target.

Then in column 10 I cut the springs to make them stiffer yet and started over.

Oh, yeah: you should leave the zip tie on the fork leg. It will tell you if your travel changes, which will happen if you lose any fork oil... and anyway, it lets the cognoscenti know you're hip! Almost as good as tiny rubber balls on the edges of your tires.