A tidy, low-mileage Honda CB1300 that came through our doors for a service and a remap of its Power Commander PC III, which we’d fitted to the bike previously to clean up the fuelling using the stock exhaust. In the meantime the owner had fitted an aftermarket end-can, which completely messed up the fuelling, especially at the critical on/off throttle point, and running the bike on the Dyno initially showed it was running hugely lean – not good.
It was very short of fuel at higher-midrange rpm and right at the very top of the rev range, but off the bottom it was just downright erratic, and needed quite a lot of adjustment; all symptoms of what can happen when you take away the standard can, that gives plenty of back-pressure, and swap it for an open can, that doesn’t.