I bought one of these new in 1981. I always thought of it as a blue collar poor boy street racer. Crashed it three times- low side left, low side right, and hit a car doing about 40mph. Put air caps on the forks. Cranked up the shock preload. Installed Dunlop Sport Elite's. A Winning Performance 4 into 1 Exhaust. Installed the largest Mikuni Jets available in the carbs and raised the Jet Needles up on washers. Removed the top off the airbox. Put over 30K miles on this bike and rode it at the California Superbike School back in the early 80's at Riverside raceway, back when they used Kawasaki GPZ550's for the class. I was a Rock Store Regular on this bike back when it seemed like the only thing they sold there was beer. My Ninja 300 is very reminiscent of the GS550. Very similar power to weight ratio. Two of my favorite bikes of all time.
1981 Suzuki GS550M Katana (Silver)