Ducati Sporting Club UK > DesmoDue Race Series > DesmoDue - General Questions and Chat > Air Gap

[Spjallen]

Just fiddling with my forks 748 encased in oem 620 sport stantions, whats the correct air gap and oil type please? First to answer wins a prize!

[Ghost]

Originally Posted by Spjallen

Just fiddling with my forks 748 encased in oem 620 sport stantions, whats the correct air gap and oil type please? First to answer wins a prize!

Air gap really needs fine tuning, as you need to be using all but approx 10mm of your fork travel. If you are not using it there is no point in having it. Also depends on what viscosity you are using also.

Prob start with about 100mm air gap with fork fully depressed.

[skidlids]

As Phil say its a matter of fine tuning it
I have quite a small Air Gap and have about 30mm unused of my fork travel, but then I like to run soft springs and soft damping settings to suit.

I can get away with this as there aren't many big bumps on most of the tracks, so most of the fork travel is used up under braking and I prefer my bike to hold itself up on the brakes rather than dive to the bottom of the forks, hence the smaller air gap and resulting in a stiffer air spring
So it really is down to individual prefrence

[bradders]

Kevs description fits mine too; 848 is really soft and using all the travel and its unsettling the way it dives under braking. DD bike didnt do that, and had about 20 mm at least of unsused and had the bumpstops removed. Amost like a beemer...

[chris.p]

Is all explained her Simon, download the file and print off a few copies and use them for each circuit you visit.

http://www.ducatisportingclub.com/sh...ad.php?t=78883


You will want a gap of 5-10mm left at the bottom of your forks after full compression ( put a cable tie on your fork leg, go out and brake hard, the distance left between the cable tie and the bottom of the fork stantion is the gap), the smaller the gap the better the turn in of the bike after breaking into a corner. if the forks rebound to quick, you will also find the bike will drift out on the exit of the corner, if this is the case try thicker fork oil.

This document will help explain problems and remidies


Chris

[skidlids]

I look forward to hearing how Simons testing goes and what he ends up with.
I will still maintain setup is an individual thing, so you need to go out and test and find out what works for you.

Even for the same Bike and rider but with different forks, you should end up with the same settings but possibly different measurements, especially in a case where fork leg outers and inners may be a case of mix and match

I have two sets of forks here both are for a 916/955/996/998
A set of Ohlins FG Widetrack Superbike forks and a set of Marzocchi RCA50 Forks

Fitted with the Same rate Springs and the damping can be set up the same. Set so the spindle is the same distance from the bottom yoke and the same amount of sag

If I set the Air Gap so that the forks travel 120mm
the Marzchozchi RCA50s would leave a tie wrap with 20mm short of the lower leg
where as the Ohlins FG Wide track forks would have crushed the tie wrap ino the lower fork leg

Alternatively I gould set the air gap for 110mm of travel leaving the Marzocchis with a 30mm gap between the tie wrap lower fork and with the ohlins a 10mm gap

Both forks are set up the same to suit the bike yet according to some of the information I see one set will always be wrong how can this be

[Spjallen]

I currently have an air gap of 140mm and I use 5w fluid. The tie wrap was about perfect at the end of he season. However I had a dead right hand after only five laps due to virbration and a leaking fork seal so I'm very interested in seeing how much fluid is in each individual forks when they are serviced shortly. New seals are a definite!

[bradders]

Blimey that low eh, I was usng a 50/50 split of 7.5 and 15 wt in mine with about 130 from memory, but no idea what was in the A bike as difn build them but suspect pretty heavy oil

[Chaz]

Im surprised you had a leaking seal in such a short time Simon, & there must be something amiss to cause the vibration, I'll be interested to know what you find.

[Spjallen]

Yeah me too! Bike was great until I crashed at oulton. Maybe the forks are out now? Ill check them at the weekend.