Front fork air gap
- Thread starter tobster
- Start date
Dellortoman
Hero member
- Location
- Tasmania, Australia
It's only madness if it doesn't work. If you manage to improve the suspension, you're a genius 
Laverdalothar
Hero member
- Location
- Germany
have no particular experience with the 500 fork (assume its a Marzocchi 35mm?!?), but air gap in general depends on what you use the bike for, what weight you are etc.
You should fill only as much oil in it, that the fork does not bottom out when you brake hard. If you overfill, the fork will block to early and you take away positive fork travel.
You should fill only as much oil in it, that the fork does not bottom out when you brake hard. If you overfill, the fork will block to early and you take away positive fork travel.
blab
Hero member
- Location
- Adelaide South Australia
What causes fork seals to instantly blow ? Stanchions in good condition.
Laverdalothar
Hero member
- Location
- Germany
Oilseals leak when stanchions are bent, you are not using a mudguard or fork brace or stanchions chroming shows wear/damage. It can also happen when the chrome on new stanchions was way (!!) to thick, as chrome is applied not in a straight line but thinner on the ends of a tube and thicker in the center...
If stanchions are good, it can be a to low air-gap/to much oil and to hard braking... On the 500 and if I am right with the 35mm Forks, hard braking can make the fork flex drastically, which can cause an oil-leak at the fork-seals... Also the wrong fork seal type or just 1 instead of the 2 I think the factory (or some dealers...) applied can be a reason...
this is all for relative new fork seals. Old ones simply get cracks.
If stanchions are good, it can be a to low air-gap/to much oil and to hard braking... On the 500 and if I am right with the 35mm Forks, hard braking can make the fork flex drastically, which can cause an oil-leak at the fork-seals... Also the wrong fork seal type or just 1 instead of the 2 I think the factory (or some dealers...) applied can be a reason...
this is all for relative new fork seals. Old ones simply get cracks.
T
Terry Dymond
Guest
Are your forks fitted with the one way valves in the caps (as on an RGS)? If so, could the valves be blocked, causing over-pressure in the forks under heavy braking.
Laverdalothar
Hero member
- Location
- Germany
Not personally, but if you buy something off ebay, you don't know for sure if it hasn't been re-chromed without that grinding... I was asked that question by a suspension specialist when I told him about a bike we had in the workshop and couldn't find the fault for weeks/months.
sonicboom500
Hero member
I spent some time ages ago fiddling around with air gaps and preloads until I got a happy medium for the roads I was using mine on.
I found that the oil difference between too much dive/vague and too harsh/abrupt on the bumpy roads I usually ride on was quite small.
Once I found the bracket levels from when I felt an obvious difference each way I set the level in the middle and tried a little each way until
I found the best balance.
Made a little tool with brass tube and a disc that I can just stick on top of the fork leg set at the preferred level and suck out the excess with a Mityvac or syringe.
I found that the oil difference between too much dive/vague and too harsh/abrupt on the bumpy roads I usually ride on was quite small.
Once I found the bracket levels from when I felt an obvious difference each way I set the level in the middle and tried a little each way until
I found the best balance.
Made a little tool with brass tube and a disc that I can just stick on top of the fork leg set at the preferred level and suck out the excess with a Mityvac or syringe.
sonicboom500
Hero member
It's probably not really helpful to apply the settings from a different bike and rider and may well cloud your perceptions of changes you make.
I started at the recommended level and worked down and then up in 5mm steps using the same representative 30 mile test route and making notes at each change.
Found the changes to be non linear between the end points.
Here are some variables for you.
Mostly used on winding A and B roads with fairly rough but grippy surfaces.
My bike has longer pre-load spacers and Progressive springs fitted which displaced more oil than the ones it came with.
The forks are lifted 15mm through the yokes.
The bars are almost vertical when viewed from the side as I sit well forward with more weight on the front end.
I am 5'11" and weigh about 12.5 stone.
Tend to use BT45s but at slightly lower pressures than standard.
Have Koni dial-a-rides fitted at rear on their lowest spring setting and middle damping setting.
All these things will affect the way it feels, so when it feels right for you, it is .
I started at the recommended level and worked down and then up in 5mm steps using the same representative 30 mile test route and making notes at each change.
Found the changes to be non linear between the end points.
Here are some variables for you.
Mostly used on winding A and B roads with fairly rough but grippy surfaces.
My bike has longer pre-load spacers and Progressive springs fitted which displaced more oil than the ones it came with.
The forks are lifted 15mm through the yokes.
The bars are almost vertical when viewed from the side as I sit well forward with more weight on the front end.
I am 5'11" and weigh about 12.5 stone.
Tend to use BT45s but at slightly lower pressures than standard.
Have Koni dial-a-rides fitted at rear on their lowest spring setting and middle damping setting.
All these things will affect the way it feels, so when it feels right for you, it is .