After fitting the Quill can, I was initially so impressed with the top end power that I overlooked the ‘hole’ in the midrange. The problem shows when you are say behind a car, drop down a gear and snap the throttle open to overtake. Rather than instant power, it kind of builds up steadily over the next 2000rpm. This was further highlighted by following some other bikes, where, in similar situations they would pull out a couple of bike lengths before my engine came on strong and recovered the ground.

All this is characteristic of poor throttle response from the engine not getting enough fuel. Hence, it was back to DSD for re-jetting.

Rather than fitting a Dyno-Jet kit, the boys at DSD decided just to fit the main jets and drill out the slides. Whilst this made no difference to the power* curve, the throttle response – either opening from closed or steady throttle- showed gains of up to 11bhp. The main difference was allowing the slides to open quicker.

It should be noticed that the before and after power curves (below - I will include these when I sort out a software problem) are similar when a full run is performed. However, out on the road, it is rare for a 1000 - 12500rpm run to be experienced. Most occur from part or closed throttle some way up the power range (to some extent, this also happens when you change gear). This is exactly the area that this mod targeted.