I believe it is 10W. Keep in mind that if you go higher weight, it will affect all your suspension movement, not just under braking. It will be much harder over small bumps and the ability to recover (rebound) will be much slower as well.
Tread carefully here. Did you set sag correctly and have the right spring rate? I don't know if you have the same setting adjustment as the later models do. I would tweak those first. Improperly setup suspension can cause loss of control and cause accidents. I am totally serious about this.
Don't just focus on one area. Take a holistic approach.
A forum community dedicated to Kawasaki Ninja 1000 motorcycle owners and enthusiasts. Come join the discussion about superbike performance, racing, modifications, classifieds, riding gear, troubleshooting, maintenance, and more!