Bonneville America Forums Forums Technical Forums Performance Mods simple tasks have me guessing.

From looking at your set up in your signature 40 is too small 42 might do it since you have the stock air box still if not then 45. Greybeard is correct adjust 1 carb for best idle with both cylaners firing then same for second carb. Then back your idle down to where it should be. When balancing find the biggest fan you can or 2 even and put them in the front of the bike to blow air across the engine to prevent over heating.