I have put about 300 miles on my bike now and wonder if I am having a carb problem or is this typical engine response. 1997 1200 custom sportster all stock with the stock screaming eagle exhaustm with 21,000 miles. Bike starts up fine and slowly adjust when backing off choke takes a good 3-5 minutes to wean off choke. Experiences a few "chug" sounds at idle with slight reving. With easy excelleration and low RPM cruising it still does some quick "chug" noises. When cranking throttle hard it runs well. When slowing down to a stop it has had a slight backfire a few times. I am not sure is the "chug" sound becuase the bike is staving for fuel? Do all stock harleys do this? Should I run carb cleaner through the fuel or take it in to have the carbs checked or even change out the jets. As you can tell I do not know much about carb adjustments. I just changed the fliuds and changed the plugs. Plugs looked good and made no difference. Any suggestions?

 

If it was my 13 year old bike I would pull the carb take it apart and clean it, there could be almost anything in a carb that old and while I had it apart I would make certian it was jetted properly the slow jet should be a 45 and the main jet should be a 175 also check the rubber diaphram that pulls the slide up and down the make certian its not cracked or torn.

 

I'm no expert, but in the the spirit:

- the choke time sounds correct,
- if the 'chug' is a misfire, _and_ happens at lower revs, _and_ happens in somewhat cooler conditions, you may be okay and may just have to make a conscious effort to keep the revs up during the first 10 minutes of operation,
- otherwise you might be running lean and might consider paying for a dyno / carb adjustment (while you're at it you could get the new pipes you want).

Hopefully you will get better help than this.

 

Yep, sounds like the carb to me too. Sounds like a jetting issue...

 

The clue is the fact that when you run at wfo and theres no pop/chug.
Under wfo you are using the main,tube and needle to some extent.
Sounds like an undersized pilot,or its slightly restricted/not fully since it Will idle.

 

My02 Hugger and my Nightster which is fuel injected "coughs" once in a while when it isn't at full operating temp. nothing to worry about. But a carb cleaning / inspection may be in order for you. I would try a couple tanks with Seafoam first and see if that helps.