The size is 159 - 0 for this model. Using a calculator there is a way to determine exact size for other models as well.
GN4 Honda oil only.
10w-40 G4
Check the manufacturers manual.
yes, I use to race a 400ex also and I have a yzf250. they are both great starter bikes.
size 622
Any kind of DOT 3 brake fluid.
You can use 10w30 in the summer. I suggest you purchase at least an owner's manual. Preferably a shop manual. Check out ebay.
To use the Jet you have to go to the Hangar in HQ (number 3 on the elevator pad) then walk out into the open part, go to the right of the open part and the jet should be there.
typically times new roman or cambria, and size 12
i use a 20w-50 jaso rated oil. the 50wt. because its an air cooled motor
size 20