The VN900C owner manual says:
F = 40psi, R = 28psi up to 97.5kg or R = 32 psi up to 180kg
The dunlop website for Kawasaki VN900C OEM D404 tires says:
F = 32psi loaded, R = 38 psi loaded
see
Fitment Guide for Dunlop Motorcycle Tires
The Kawasaki dealer adjusted mine at the first service to:
F = 32psi, R = 36psi
I found this a little wishy-washy around corners so have adjusted them to:
F = 36psi, R = 34psi
I weigh ~ 75kg in my riding gear and the bike has a sissy bar and rack ~ 5kg
I also noted that Dunlop recommends a 1.85 inch rim for the 80/90-21 tire, while Kawasaki is running it on a 2.15 inch rim, which may account for why Kawasaki recommend higher front tire pressures than Dunlop.