Hi Pete, my advice would be : 10T front sprocket, slow action throttle (Black Tube), Flywheel weight, definitely re pack tail pipe, middle box packing would make a difference, but is quite difficult to do, Carb settings which I find best assuming you have the std Dellorto Carb fitted are Main Jet 118, Pilot Jet 33,Slide 50,Needle D33, on 3rd notch from top, also mixture screw approx. 3 full turns out, also bear in mind that as its a mixture screw as apposed to an air screw, its out to richen , and in to weaken, any more advice you need just ask, will be happy to help.