i have a 1998 FXDWG with a S&S 111" motor. been riding it daily for the past 2 months with out any problems. then out of nowhere it started to spit and sputter and run like crap. if i hold it at a steady throttle it will run somewhat smooth then it'll start doing it again if you go to wide open it will take off just fine then when just coast down to 40-50 mph it wont run for ****. i put a brand new Super G carb on it and have put the same exact jets in that has always been in the motor and cant get it to run right. running out of ideas and what to check.

 

Have checked for water in the fuel, tank and carb. Another, if you have a vented gas cap the vent may have become obstructed, little bugs look for holes to live in.

 

brand new gas tank with tank liner and all vents are brand new.

 

clean the jets again, check fuel level, check for vacuum leaks and blocked air intake or air filter, clean and check plugs. Lastly start checking the ignition coil and system

 

everything is brand new on it. brand new coil, plugs, ignition, new air cleaner/ filter, lithium battery, new carb, brand new jets. have tried different jet combinations. i can sit here in neutral and rev it to the limiter with no problem or hesitation its as soon as i go out and ride it, it has problems. tank is full with fresh 93 octane gas. no vacuum leaks i have checked all that. im not for certain but it feels like something is cutting in and out like electrical.

 

underload it is giving trouble which usually is a fuel issue, Double check that the airfilter is sealing off properly and not allowing air to bypass it.Double check the compression on both cylinders as well. I know the carb and jets new, but still clean it out again. Also check fuel flow from petcock and fuel filter.

 

Under load, could also be spark. Coil can be breaking down.

 

When was the last time you replaced the hose between the petcock and carb?
They rot from the inside from the ethanol.

 

Recent ride with buddy who was on his '16 Dyna experienced similar, turns out it was a loose cable connection at battery.

 

its brand new replaced it with the tank along with the crossover tube and vent lines