Chosen Solution
1987 Sportster 883. 1200 heads, s&s E carb, upgraded s&s air cleaner. Was breaking up entire range. Main jet from .070 to .074. Pilot jet from .028 to .030. Much improved but still slight break up mid range. Should i increase either jet, both, or maybe air bleed. Break up is in carb like a fuel starve.
@firstharley if you are only breaking up at between 2000-3500 but not above and not at idle leave the pilot alone and concentrate on the main but before you do look for vacuum leaks . Check the oil for fuel you can get the same miss with a rich burn . Whats your plugs telling you ? Do you smell fuel at all?
