Seem to be having a problem with my WS7 keeping a tune? Starts out great then about 1/2 tank run it looses it,,,,, it feels FAT,,,, any help, any starting points? Using 20% Sidewinder, OS #8 plug, OS 2050 pipe,,, has 1 thin shim in the head,,,,thanks. Also what are the factory needle settings for this motor,,, no turbo, standard plug,,, PLEASE HELP