Adding propper fork air pressure

Joseph New York

Active Member
Hi, my first post here! Hopefully its not a dumb question :/

When air pressurizing the forks, should the wheel be off the ground or not? Neither manuals specify.

More info:

Two of my CBs ('81 CB650 & '81 CB750C) have air assisted forks and I've maintained the pressure range on both to spec: 10-16 psi

In both of their Clymer manuals, the parts specifying adding the air pressure, differ. On the 650, the front wheel is removed and on the 750 manual the bike is on it's center stand. I'm a literal person, so for pressurizing the 650, I lifted the front wheel off the ground, and for the 750 I put it on it's center stand when pumping up.

Added weight on the forks obviously increase the air pressure, so when pumping I can't assume their pressure readings are consistent when matching to their matching specs. As it turns out, the 750's suspension is decent, and it feels that the 650 is too limp. Simple physics would suggest this.

One final point... Both CBs have clip-on handlebars. This weight distribution to the front is greater since my posture leans forward and my body weight is on the front instead of the center like the manual expects. With this said, I decided to add the max (16psi) to both forks. I'd prefer to go more but I don't want to break the seals.

When pressurizing the forks, should the wheel be off the ground or not?

Thanks!
 
.
it is easier to replicate the results with the wheel off the ground . . you can reduce the amount of air a little by preloading the springs 3/4 - 1".

increasing fork oil viscosity might also help.
 
The correct answer is the forks should be fully extended when measuring and adjusting the air. The wheel can be on the ground as long as the forks are fully extended.

It is easier to tell the forks are fully extended when off the ground, but some bikes, on the center stand will cause a fully extended fork.
 
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