I usually hang out over on the Classics page (Ironheads) but also have a 2003 FXDL, in addition to my old ironhead. This item may have been discussed before and if so, please let me know.
My Dyna has 4400 miles on it and suddenly it began to idle rough and spit back through the carb when I took off at a red light. At times it would even die, but start right back up.

I put new plugs in, although the old ones were fine, as they should be with only 4400 miles on them.
I checked the resistance on the coil (both primary and secondary circuits). Both were within spec.
I pulled the float bowl off expecting to find water or trash inside, but all was clean.
I pulled the entire carb off and dismantled it, finding everything clean as a pin inside.
I had reached the point where I did not know what else to do. As I usually do all of my own work, it really hurt to take it to a dealer, but I was frustrated and had little choice.

The mechanic found the problem within 45 minutes.

Built into the float bowl body is a ball check valve that resides inside the accelerator pump nozzle (a brass tube sticking up on the bowl). He told me the ball had stuck. I said that the accelerator pump was working fine, shooting a stream of fuel out when I opened the throttle.
He agreed, but told me that at full throttle the pump pressure bypassed the stuck ball. With a slight crack of the throttle, no fuel got pass the ball and the result was a lean mixture. That all made good sense to me.
I asked him how he found this stuck ball and his reply was too simple for words. 'I shook the bowl and nothing rattled.' He had soaked it in carb cleaner for twenty minutes but it remained stuck. So, I ordered a new float bowl to fix the problem.
Now, the first thing I did when I got home was to open the parts manual. The parts manual shows the float bowl and the tube sticking up, but no sign of this ball check or call out of the tube.
I opened the repair manual and there the tube was shown and called out as 'the accelerator pump tube' but nothing was shown of the ball check inside. I never would have found that darn thing! So, for once I must say that for the $82 spent at the dealers, I walked out a happy man.
Has this happened to anyone else? Like I say, I don't get to this site that much.

 

Well I'll be damned - my carb'd '04 Wide Glide is exhibiting the same symptoms. I am going to pull the float bowl and check it out. It's been driving me crazy.

 

I've got an 02 carbed FXD and I have never heard about that checkball. If the carb is stock be real careful and drill the plug off the fuel/air mix screw and turn it out about an 1/8 to 1/2 turn this could help the rough idle and definetly cure the lean idle mix "carb spitting" AKA "carb farts" when coming off idle applying throttle from a stop. The carb farts are a product of EPA lean conditions and are very common on carb HD bikes.

 

I just got done pulling the float bowl and the checkball is there and unstuck because I can hear it rattle when I shake the bowl. So, I cleaned the bowl and the AF and it seems to be doing OK. I still need to adjust my idle mix and idle speed though. My carb is already drilled and jetted for stage one. From the documentation I read, about 2 to 2.5 turns out is a good starting point for CV carb adjustment. Mine is currently at 2.5, but I still need to follow the step by step procedure I read here: http://www.harley-performance.com/ha...arburetor.html

I have only set the adjustment to 2.5 turns and left it at that - that may be the reason for my trouble.

 

Yes. My 2003 is doing the same thing. I will try the new bowl. Thanks