Avid readers will know that we've got a pipe on our long term Suzuki GSX-S750 now, and so we really need a Power Commander, to get the best out of it. Okay, a slip-on can like our GPR Exhausts one maybe isn't going to make a massive difference to the fuelling needs on its own. But - our man Sean Mills at Big CC Racing reckoned the stock GSX-S was running a little on the rich side, so there was some fettling to be done anyway.
Now we can do two birds with one stone, and get the air/fuel ratio spot on to suit the can and resolve the stock over-fuelling. The good folks at Dynojet UK have sent us a Power Commander V for the GSX-S750, and we'll be bolting it on as soon as we get a minute... It's a simple enough job - the main pain is gaining access to the injector plugs under the tank. The Dynojet unit taps into the fuelling signal between the ECU and the injector, tweaks it to what it should be, then sends it on to the engine side of things.
We've also got an extra little box, which is for the oxygen sensor in the exhaust. The ECU uses that sensor to alter the fuelling on the move, so if you keep it in place, it interferes with the Power Commander's work, and tries to reverse some of the changes the tuning box is making. This little box of tricks replaces the oxygen sensor, so the bike thinks the sensor is still connected, and providing the correct signal. Then, the stock ECU doesn't interfere with proceedings. Cunning, huh?
Once the PCV is fitted, we'll schlepp down to Big CC, put her on the Dynojet 250i rolling road dyno there, and Sean will re-map the fuel all the way through the rev range, for optimal results. And maybe even some more ponies!
More info on the Power Commander here.