MK 11 Front Forks

[jeffc246]

I am after some info regarding front forks on my Mk 11 Frontera.
The forks are fitted with air valves, is this standard? and if so , are they for increasing the stiffness of the forks, and how much pressure should run with.
I have been advised that they may be there to release built up pressure.
Also , could anyone advise as to how much oil (cc) should be placed into each tube.
Again I've been advised to run with 20 weight, is this also correct.

any help would be appreaciated.

Thanks

[David Lahey]

It was popular in the late 1970s for bikes to come with air caps and they were usually used as a tuning aid - ie there are steel springs doing most of the work and you change the air pressure and oil level to adjust the preload and overall spring rate. If your forks still have the steel springs inside, the air pressure with the forks topped out should be in the range 0 to 6 psi. Due to the small air volume, it can be pretty tricky to get the pressure where you want it.
I rode a friends Mk11 Frontera in Pony Express events in 1978 but didn't notice air caps on the forks so I don't know if they are standard or not.
Fork oil weight is a personal preference thing and depends on your weight and how hard you ride. 20WT is a good starting point.

[jeffc246]

Thanks for the advise.
Will leave the air out for now and go with the 20 wt and see how she handles

[Bullymad]

As feetup said it was popular in the 70's

The problem is that the air will get hot the more riding you do.

So like a tyre the pressure will increase making the forks more rigid

Stick with the 20 weight oil mate