Ok so I have a 99 summitX 670, its bored over a little to a 680 and has a set of CPI twins on it and a 501 rotary valve. I ride around 6500 feet or above. Any help on jet sizes?? Its also clutched regeared and a 153 track
I would start with 420-410's mains
55 pilots 1.5 turns out on the air screws and stock needles in the middle. If the engine is stock other then the twins this will be close.
