One of the issues that’s confounded me most with the GSX-S1000F is the way it makes its power – and this is further compounded by its throttle response. So I took it for a dyno run at BSD Performance to see how it compares to its ancestral twin, the GSX-R1000 K5.
The result is fascinating. The smooth lines show a standard GSX-R1000 K5, while the wavy ones are the GSX-S. The interesting points are where the lines separate.
The K5 curves both rise majestically to their peaks, with arcs that you couldn’t dramatically better. The GSX-S looks more like it’s been drawn freehand by someone with the shakes. But this isn’t all Suzuki’s fault.
The bikes were built to wildly different emissions regulations that now strangle the GSX-S, and Suzuki have to tread a tricky line between optimal performance and those pesky regs. Don’t forget that the GSX-S also has a lower rev ceiling than the GSX-R, inhibiting its ability to make power, uses more road-focussed cams, has a lower compression ratio and a different exhaust system, too. They’re twins, but by no means identical ones.
This all results in a sinkhole that a geologist would be proud to stare into from 4250-7250rpm in both curves. It’s an engineered deficit, which later vanishes, and once clear of its stutter at 8250 (likely caused by the secondary butterflies), it builds to a strong 147.48bhp at peak – 4bhp more than Suzuki claim.
What isn’t explained is the snatchy throttle response, which is at its worst at partial throttle openings. I’m hoping this can be rectified by tweaking the fuel map to both iron out the saggy points in the curve, and reduce the amount of fuel initially dumped into the throttle bodies. Once sorted, my single biggest GSX-S niggle will evaporate.