So I recently bought a 1996 sportster that hadn’t ran in years. I got it running and did a tank flush and a thorough carb clean. Set to s&s settings. Bike started first try and runs. Today I rode to work first time. Has a flat spot 1/3 throttle stumble with occasional pops out the carb. Gag the throttle and it runs great. Flat spot seens to be between 30-50% throttle approximately. Pulled a plug when I got home and it looks a little lean but not dangerously so. If you snap throttle from idle it will stall, but from 1500 will spin right up. Comes down fast also. Seems to be intermediate circuit with my minimal tuning knowledge. Has S&S G, S&S air filter and long skinny drag pipes. Low jet is .0295 main is .074. I’m new to the Harley scene and hate my first one has carb issues already. I’m tempted to put a cv carb back on since I have more experience with them on my Suzuki’s

 

Check for intake leaks. That jetting sounds really rich for a Sportster.
Drop the main jet down to a 70 to start. May need even smaller. Ensure idle mixture and accelerator pump is properly set.
i would guess that you’ll end up around a 28 int and a 68 main.

 

i really appreciate the feedback! I thought it behaved very rich, but my plugs are white tan without a hint of carbon or fouling. And no soot in pipe. I did find a crack in a vacuum line and repaired and although it accelerates better it still breaks up at a cruise. Seems like I’m having accelerator pump issues on throttle snap, but that wouldn’t explain having to ride high rpms or low rpms to cruise. It will run fine lugging along or if I accelerate. Popping and coughing from the carb indicates lean correct? Especially with tan plugs. But using the choke doesn’t help with the flat spot and spitting

 

sounds like its too rich, I'm trying to dial in my my new S&S right now also, have you reset the accel pump? I hear drag pipes are terrible for tuning on S&S carbs. If you got this corrected i'd be curious to know what fixed it, Thanks.

 

So it runs beautiful now. The issue was having such a large carb it had too low of vacuum at higher rpms. I replaced a 31 jet, and took a razor blade to flare the accelerator pump nozzle slightly. Took a bit of tuning afterwards but I’ve already put over 1k miles on it since the repair. Never sputters or spits. Great torque, and it never falls on its face