I am confused just now, cause some papers show, that it shall be 160mm and some mention, that 180mm. I am quessing, that in 750/906 forks it shall be 160mm and in 907 180mm, but Ducati workshops cant help, cause there are many faults in those, so does anybody know right level 100% SURELY. I dont need amount of oil, but level measured from top in mm !!!! ...and FASTLY, please!

I mean slider compressed and without spring, as it must be measured.....

Hi Antti

original Marzocchi workshop book says 180 mm.
I put in WP progressive springs without spacers and oil level 160 mm.
this avoids bottoming, because the airpressure builds up more rapidly.
I would suggest to start with 180 mm. This is also related to your bodyweight.

So, goodluck with your selection

I have also that manual for it (5/88(year?)), but its maybe for 750 Paso and 906, cause fotos seems such, like caliper holes are like in 750/906. And 907 forks are at least slightly different, like also that seal area, maybe also travel is different(caused by 17" wheels in 907).

I have 12cm of air gap for the forks and 16.5 psi to stop dive. The standard 18cm makes the fork action too prone to dive (especially with steel brake discs).

Hi Annti,

I will check the White Power manual.
12 cm level and 16.5 psi??
It seems a little to much to me. I would go for non-pressurized.
travel is about 120 mm. negative riding hight should be about 30 mm. (app. 25 % of total travel) If you're far of the spring isn't right. as you selected the right spring and the fork is still bottoming, add up oil. (making the airspring stiffer)

ducbertus

This "inside pressure" is very strange, cause i have allways taught, that M1R inside pressure should be 0 and those air valves are only for taking out that air, what "leaks" via seals to inside??? That happen, cause i have noticed, that if i push air pressure valves some times/summer, then air is coming little out from there. I have noticed, that others think, that there should be inside pressure and another thinks, that never..... this have been discussed earlier, but i am too lazy to search it.....

My weight is 73 -77kgs depending, how much i have eated/drinked ( ) and i use normal stainless steel rotors in this 907.

I cant trust to Ducati workshop manuals at all, cause there is sooo much mistakes with these all measurements (some say, that 160mm and some say 180mm...) and nothing about viscosity. I have used till today 5W and 7.5W fully synthetic.... Also i use normal springs. and surely front end shouldnt be too hard, but also it shouldnt bottoming...

Hi Antti,

I wouldn't apply any pressure in the fork, like the manual suggests.
If you apply pressure, the innerring of the seal is pressed with force against the innertube causing even more stick slip as we have already.
you can play with different viscousities of oil in the left or richt leg. Oil level needs to be the same in both legs.
You are not a heavy guy, so you use let say 160 to 170 mm to start. then try a bad road and heavy braking. if it isn't bottoming, you're fine.
if you put a tie wrap around a stanchion (not to tight of course) you can see how much travel you use.
I think you can't set up the system in one time right.

ducbertus

Gas pressure for a front fork wasn't unusual during the 80's, plenty of Hondas had the facility. If I run the 906 with no fork pressure I get a speed wobble (different rear shock & taller profile rear tyre) so it works for mine. I wouldn't go along with the user manual too much anyway. Trouble is without fork pressure the front suspension travel is reduced so why not make use of the extra air valves.

Hi Antti,

Checked the recommendations of White Power according to the oil and oillevel
they say: SAE15 oil and 150 mm oillevel.
I've followed this and sofar I'm happy with it.

DucBertus

So, i cant go "far", if i put to 170mm level?

I think you can start there

ducbertus

Both forks are rebuild now with new seals and dust scrapers and i put to both 175mm level with 5w fully synthetic fork oil... we shall see.. we shall see... btw, no inside pressure...

Roughly how much oil is required in the standard forks to arrive at the air-gap level? I've not seen it mentioned in any of the manuals or on this forum anywhere... I bought a litre... but I've a creeping suspicion that's nowhere near enough.

thanks in advance.

That will be enough. You'll probably end up using ca 700ml or so.

My 2 cents:
Fill the forks with oil leaving an air volume at the top of 180 mm (see drawing from M1R shop manual page). I do this either before or after I put the forks back on the bike. The way I get the 180 mm air space is I took a thin tube of copper from the hardware store (because it is stiff and will not bend) and attached a drill bit stop collar on the tube to set the required length. I over fill the fork slightly with oil. I then take my copper tube and insert it in the hole at the top where the air valve screws in. Now I have allowed for thickness of the fork cap and all so that from the fork cap to the end of my tube I will get the 180 mm distance. So with the fork slightly over filled, and then using a syringe and a short piece of rubber or plastic tubing to connect the syringe to the copper tubing, I remove the fork oil until the syringe will not suck up any more oil and this will leave me the required air space. Easy.
I have read, and been told, and researched about the air valves. They are for releasing air pressure that builds up and not for pumping up or adding any air pressure.
Another note. From my experience the OEM fork seals, the original part number seals will leak in almost no time. I can't tell you how many times I have replaced the seals with the factory part and they leak. No burrs on bad places on my forks, they just leak. I use the fork seals from the 90s 900SS. They are same diameter however the hard rubber covered metal body of the seal is a little taller. So I omit the washer and trim a little of the rubber off the bottom of the seal, seat them in the fork tube then use the Cir clip as normal to keep it in and the factory dust cup after that. If you look at both seals side by side you will see the 900SS seals are more robust. I have not had them leak in 5 years or more.

du907