Specs: 2003 HD Sportster 883C
Hyper-charger with aftermarket pipes. Carb is jetted at #45 & #175 (Carb has been jetted like this for over a year)

I recently did some ignition work to my sporty. I replaced the ignition module, ignition coil and spark plugs.

My sporty is now sputtering while in low RPM's. When I'm sitting in neutral I can rev the engine no problem. Doesn't matter if I'm revving low RPM's or high RPM's it feels smooth. Once I pop it into gear it begins sputtering at low RPM's and I have to keep the RPM's up for it to ride smooth. I've spent hours adjusting the carburetor but I can't find the sweet spot.

Any idea what this could be? It's ride able but kind of annoying at low RPM's.

Thanks. Zach

 

You could just be in too low of a speed for that gear. It's called "lugging".

 

I don't think that's it. I know how it feels to be in too low of an RPM for that gear and this is something that feels completely different. When I'm in first gear at a stop and I go to take off it does the sputtering still.

This is what it's like.. I'm at a stop in first gear with the clutch in. I start to take off from a stop and I pull the throttle and it sputters. I haven't even disengaged the clutch completely yet. It's a loss of power and I have to really rev it to get the sputtering to stop.

 

Sounds like the accelerator pump in the carb isn't working or not working well.
Have you replaced the pump diaphragm?

 

cHarley - No I haven't replaced the pump diaphragm. I had the carburetor cleaned last week though. If I remember correctly the pump diaphragm is almost at the very bottom of the carburetor right? Would this involve removing the carb or could I do this while it's still on the bike?

 

Also.. If that needed replaced, wouldn't it affect me in higher RMP's as well?

 

The pump is part of the float bowl, so you don't need to remove the carb, just drop the bowl.

No, it just provides a shot of fuel when you initially twist the throttle.
You can tell if it's working by removing the A/C and looking into the throat of the carb as you twist the throttle. There's a small metal tube that sticks up into the carb throat that should squirt gas as you twist the throttle.

 

OK Thanks cHarley. I'll check that out and report back

 

cHarley - it's doing what you said. It seems to be working properly.

 

Then you may be lugging the motor (not enough RPMs). Sportsters like it in the 3500 - 4500 rpm range. Especially when your starting from a stop. Try it and see. Then we can take it from there.