Hi i have a 2000 Fat Boy(carburetor model) that I hade modified with new cams and gear drive to the cams instead of chain drive . Prior to having this done I was informed it would idle a bit lumpy at idle, but it is more than a bit lumpy it almost feels like it has a miss a low revs being very lumpy up until 2000 RPM It sound like the firing sequence is out of wack and when trying to maintain a steady speed at low revs it quite uncomfortable . I have changed the plugs and HT leads and tried different octane fuels but to now avail . By putting the bigger cams in and the gear drive the motor is a lot quieter , has more HP and runs fine when cruising over 2000 RPM . Is there anything I can do to get it to run smoother at the lower RPM

 

changing bump sticks without thinking it through can lead to such issues. ALL parts must play nice, inlet to exhaust and everything in between.
one important aspect of camming is do you have the proper compression to run the cam??? you may have lost hp and not gained anything.
not much info to really go on. the lumpy idle comes from over lap, reason why idle rpm is usually increased since mix at low rpm really isn't optimum.

 

What's the cam?

 

Yes buy a 4 degree advance cam gear, it will allow your torque to start 400 RPM's earlier then what you currently have, should make a noticeable increase in takeoff torque from idle, as well make engine idle a little bit smoother.

B Bop

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It woud help to know what cam was installed? Obvious question; did the OP rejet the carburetor? Absolutely necessary with performance cams. Starting point is A/F screw setting; may need to go up on the pilot jet.