Join Date: Mar 2005
Location: Channelview, TX
According to the Clymer's manual, standard is atmospheric pressure (0# with wheel off the ground, as above). Usable range, 0-7.1 psi.
According to my Kaw Service Manual, OEM hardcopy, covering 1985 VN700, and 1986-90, VN750-A2 thru -A6:
Front Fork Air Pressure
Standard: Atmospheric pressure (for one average-built rider with no accessories)
Usable range: 0-49kPa (0-0.5kg/cm sq., 0-7.1 psi)
The caution note following says air exceeding 36 psi may damage the oil seal. The Note above that says, "Lower air pressure is for comfortable riding, but it should be increased for high-speed riding, or riding on bad roads."
Personally, I'd not set it over 7-8 psi. Two-up, most of the weight is going to be over the shocks, except when braking; I would do most of my suspension adjustment there, anyway, as the shocks give a little more leeway. I don't think I would want to go more than 14-15 psi on the forks (per tube), no matter what the load on the bike overall.
'95 Vulcan 750 "Therapy II",
aka "Raggedy Ann"
'95 VN750 project
'03 VN800B "The Little Black"
'04 VN800E Drifter project
'93 VN1500A custom project
Photo album: http://www.flickr.com/photos/leekayd/sets