Good to see there's many SU gurus alive! I've been testing many ways to make these suckers to work on 1/2 and full race engines and here's few tricks: A. By using different viscosity motor oils you can adjust the mixture by dampening the piston travel(thick oil=lean) B. By not filling the damper up full you can enrichen the top end C. By shimming / grinding the plunger piston you can get an acc pump effect D. By grinding the piston ahead of the needle valve you can increase the air flow and change the fuel curve (look at any Japanese performance bike for the shape)E. By stacking 4 bakelite spacers between barbs and the manifold (plus longer studs)fuel won't boil = no vapor locks F. By drilling the needle jets you can feed 200+ HP (if you don't do that needle valves act like main jets!) G. By grinding the jets thinner you can adjust the mixture and mixture curve H. By stacking more cover gaskets you can adjust the float level (there's a limit how much you can bend the valve tab and they brake easily) Well, gurus out there, let me hear your tricks!