I probably sound stupid, but I have an air valve stem on each of my fork caps. I can't find anything about front fork air suspension and really don't know if that is what I have or if there is such a thing. If it is an air suspension system how many pounds of air should I keep in them on my Sportster trike? When I checked the air pressure in them my gauge read no air pressure. What do I have here?

 

Sounds like someone added the valve stems.Some dirtbikes have this set up.
The air preassure adjusts the ride quality.It doesnt require much air to change the ride,maybe 2-8 lbs.You will need a low pressure air gauge to check the pressure and experiment by changing the air pressure.
I think you can get a better quality ride without the air by changing the spring rate and or the valving.
Are you having a problem with the forks/dampening?

 

Thanks for the reply. I am just trying to so for a little smoother ride. It does seem to dive more than it should when I hit the front brake very hard.

 

It's possible someone added the air to correct weak springs.I dont think air is the correct way to fix the problem.
I think I would change the fork oil and buy some Progressive fork springs.

 

I found a little info on air forks. They are used as a pre-load adjustment and you only run a few pounds of pressure in them. I'm lucky I didn't blow a seal the first time I put air in them. I used an air hose at a filling station and found out later that it's a big no-no. I got way too much pressure in them. I've found that one shot with a bicycle hand pump will put about 5 to 8 lbs. in the fork and that's plenty. Funny thing is I searched the internet hard and never did find out much about air forks and nothing on them beingon a Sportster. I think this has to be an add on by someone since there is nothing about this set-up in my Spotster service manual that covers years from '91 to '03.