should be on the left side of the motor just above the crankcase has a screw on lid and their should be a sight glass were you can see how your oil is when the bike is standing straight up.you can buy an service manual right from suzuki and it covers everything it is thier service manaul about 50-100 beans for the book
just picked up a 92, i downloaded my service manual from a link on www.gixxer.com i cant remember where exactly it was on there, i did get a free manual..i could send it to ya its i THINK 91-95?