Air Pressure in Forks?

[mcycle-nut]

What's the concensus on running air in forks? I have never put air in them as I'm afraid of blowing the fork seals. I have an '82 1100EZ, an '83 1100 ESD, and my wife has an '82 850GZ. All of these bikes have Progressive Suspension springs in them.

[AMK]

I have stock forks/springs and like you I don't want to blow seals.
On my Honda 350x I have air forks and I started to lift the front wheel off off the ground and open the valves to allow the forks to assume atmospheric pressure. That way I didn't blow seals.
I've been doing that with my bikes as well. I feel it equalizes pressure without adding any.

[Steve]

If you already have Progressive springs in there, you should not need to add any air.

However, you do need to set the preload, which is one thing the air was supposed to do.

To determine whether you have the correct preload, measure the "sag".
Sag is how much the suspension compresses between fully-extended and your riding height.
Easiest way to check is to have a helper. Put the bike on the centerstand, measure from the top of the dust boot to the bottom of the lower triple clamp, record that number. Put the bike on its wheels, get on the bike. Get into your normal riding position, bounce the bike a little bit to settle it into its preferred height, have your helper get the same measurement, record it.

How much is "proper"? General concensus seems to be 20-25% of total suspension travel. Most of our forks have 5-6 inches of travel, so you are looking for about 1-1.5 inches of sag. If you have more than that, add the difference to the length of the spacer that is with your springs inside the fork.

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