this had the 340 mains clips in the 3 position with one shim on bottom and one on top. yesterday was 39 deg so i went to the 320 main (20+ to 40f) felt rich on the slide so put bottom shim up top last nite. thing is my pistons have no carbon on em. Im burning to much oil i think and my plugs work but are oil fouled. any tips? did 70 miles and about 10 gals of gas think im seeing about 7 mpg on this sled. should mention I belive this is the single port motor. Im guessing this is why my jets are smaller than the ZR580's. i hear many of the cat's were few jet sizes rich. my sled revs clean but my plug color and piston wash is garbage also could this be bad check valves and over oiling causing shiny domes?