Motorcycle Repair: back firing, air fuel mixture, intake leak

Question
had a S&S super E installed, on '89 ElectraGlide,
and occasionally, it was back firing after warming up. resetup rpm idle and air/fuel mixture
and it runs smooth but back fires like crazy when starting up, even when warm.
checked spark, rear cylinder fine, front seemed a little weaker though that could of been subjective. connection to plugs is good, and to
coil as well. spark plugs i've pulled out have been very carbonized, black.
need pointers from here.
bike has a EV27 cam and true dual exhaust.
was considering having it Dyno'd, but shouldn't
i resolve the back firing first?

Answer
BACK FIRING IS FROM A INTAKE LEAK, THE EXHAUST IS ALSO NOT HELPING THE MOTOR. GET RID OF IT AND BUY A EXHAUST SYSTEM THAT WORKS!! WHITE BROTHERS E-SERIES 2 INTO 1 EXHAUST SYSTEM IS THE HOT TICKET!!  MORE POWER AND TORQUE ACROSS THE ENTIRE POWER BAND AND THE BIKE WILL RUN MUCH HAPPYER. YOUR JETTING IS ALSO WRONG. WHAT JETS ARE IN THE S&S CARB?. ALSO THE S&S CARB NEED A THUNDERJET AND TUNED CORRECTLY ON THE DYNO WITH LOAD CONTROLLER AND AIR/FUEL MONITOR, THE EV27 CAM IS NOT A VERY GOOD CHOISE. I WOULD INSTALL A HEAD QUATERS 0024 CAM AND MAKE SOME VERY GOOD TORQUE AND HORSE POWER. JOHNNY
www.southsidesdyno.com  602-705-7474 Phoenix Az