Air pressure in front forks, 850G

[jeneralist]

So I spent part of this weekend with my 81 850G in the driveway, finally replacing the gasket around the stator cover. (I'd been dripping oil ever so slowly since I updated the stator last year. I think I finally got *that* off my to-do list.)

While I was flipping through the shop manual, I noticed for the first time the specs on the front fork pressure: between 8-17 psi, and no more than 35 psi ever, because unknown bad things will happen.

Folks, when I got the bike over a decade ago, it came with a fork pressure gauge mounted onto the handlebars. I never adjusted the pressure, because things felt right as they were -- up at 50 psi!

My first step, I know, is to see if that gauge is telling me the truth or not. Assuming that it is... how much trouble am I in? How slowly do I need to go when I back the pressure off? Was the previous owner doing something sensible -- like trying to compensate for the weight of the Vetter fairing, or the weight of a heavy rider -- that I just don't understand?

As ever, thanks for the help.

[flyingace]

My 850 couldn't hold air in either fork so I just removed all the air from both. I never noticed a bit of difference.

Ace.

[bwringer]

Air is just a poor substitute for proper spring preload. Air pressure in the forks is subject to leaks if the fork seals are not perfect, and it contributes to wear on the fork seals.

I personally think it's pretty dangerous to trust any suspension component that is subject to sudden changes. What if you lost air pressure as you're going around a fast curve or swerving around a deer?

The Right Thing to do would be to drop in Progressive fork springs to replace the sagged, worn out, and utterly pitiful stockers. Follow the directions on the package to make preload spacers from metal tubing or PVC. Try different spacers to arrive at the correct preload for your weight and riding style.

[jeneralist]

More info --

The gauge on the forks says 50 psi, but the one I check my tires with says 30. Curiouser and curiouser....

[flyingace]

Any pressure is too much. Brian is right about getting good springs and setting the preload correctly. Some day I'm going to do that.

[IanFrancisco]

I have aftermarket air caps on my forks. When I went to install my Progressive springs, there was no way I could squeeze hard enough on the new springs to get the included PVC spacers in. I think they are about 3/4in. long. The aftermarket air caps stick in to the fork legs 1in. to 1 1/4in. I never saw the OE caps to compare them but thought OK, I want to get this done and not ruin the threads on the fork legs or caps, so I left the PVC spacers off. I seemed to have enough preload without them or any air, the forks were plusher and firmer at the same time than the "pitiful" stock springs. I'm happy. I tried running about 8.5 psi in the forks and noticed they were stiffer, but not much. But the right leg started leaking a bit so I let the air out. I've hit some pretty gnarly potholes, enough to bottom out the rear suspension, but I dont think the front forks have bottomed out since the new springs went in. My bike is a lightweight, though, at 400lbs wet. Now it's time to reseal the forks I think I will try again to get the PVC spacers in. Any suggestions to make that job easier?