As the saying goes, there’s no replacement for displacement. There’s truth in that statement, which is unfortunate when you’re working with 487 air cooled cubic centimeters.
We didn’t have pre-modification baseline numbers for our 1993 Suzuki GS500, but a little research revealed the average stock GS500 puts down about 39 wheel horsepower. That’s not a lot in comparison to the average modern sportbike, but it is enough to have some fun without getting yourself into a whole lot of trouble. That said, after completing a bunch of work on the bike we were hoping to put down a few extra ponies and fine tune our Suzuki GS500 on the dyno at D&D Import Cycles.
Prior to visiting the dyno we had opened up our Suzuki’s factory Mikuni carbs and re-jetted them with a stage III jet kit and pod filters. The ignition was also re-drilled with a five degree timing advance, and we installed a full Vance & Hines Supersport exhaust system.
With the bike warmed up to operating temperature and strapped down on the Dynojet 200, dyno operator Jerry Peak shifted the GS500 up through the gears to an aggressive fourth gear roll on the throttle. Fourth gear was used for the power pulls because it’s the point at which the ratio between the rotating dyno drum and the Suzuki’s rear tire is closest to 1:1. The base pull calculated 44 horsepower at the wheel – already a very good improvement from the stock estimate. The graph also showed the Suzuki twin to be running rich.