Rough Running
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5th Gear
Joined: Oct 2019
Posts: 9
Likes: 0
From: Western Australia
Rough Running
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
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,052
Likes: 993
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.
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.
Road Captain
Joined: Feb 2013
Posts: 651
Likes: 72
From: Harleysville, PA
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
2012 FLHR (Road King) Stage II Red Ember Sunglo/Merlo Sunglo, Original HD Chrome Laced Profile Aluminum Spoke Tubeless Rims, ABS, Cruise Control, Security Package, Police Tachometer, Saddlebag LED Spoiler lights, and array of nostalgic & high performance accessories that enhances appearance & blood curdling performance.
It’s a shame there is nothing available today that can measure white knuckles & big a$$ smiles.
B Bop
2012 FLHR (Road King) Stage II Red Ember Sunglo/Merlo Sunglo, Original HD Chrome Laced Profile Aluminum Spoke Tubeless Rims, ABS, Cruise Control, Security Package, Police Tachometer, Saddlebag LED Spoiler lights, and array of nostalgic & high performance accessories that enhances appearance & blood curdling performance.
It’s a shame there is nothing available today that can measure white knuckles & big a$$ smiles.
Last edited by B Bop; Nov 12, 2021 at 08:39 AM.
HDF Community Team
Joined: Jun 2006
Posts: 12,774
Likes: 2,606
From: san antonio
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.
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