Carb cough issues
 

I just picked up a 2001 FXDX last weekend. Everything is bone stock except a full K&N air cleaner system with backing place etc. Only has 10k miles.

My issue started out with just the carb cough. I would be sitting at a light after it was warmed up, light turns green and give it some throttle. She coughs pretty hard and dies out. Then its pretty hard to start right after this happens.

This happened three times so I went to my Indie and bought a #48 jet and swapped out the 46. Adjusted the richment screw to 3 1/4 turns and it seemed to have ran great. Right at 900rpm and very smooth with no cough.

I just got back from riding and about an hour into my ride I have to stop at a light and end up having to pull the choke out 25% to keep it running. The gas smell was pretty heavy, saw some black smoke out of the tail pipe.

I'm really stumped. Do i throw the 46 back in and then adjust from there? Or am i missing something? I didnt mess with the Main jet because she doesnt back fire or sputter or lose power at the top. Runs like a dream, its just when i stop that it acts like its on super low idle and sputters out.

Any suggestions on what to do here? I have noticed on two different occasions, right after the loud cough and stall, a small plume of white smoke comes from the carb.

I really just want to be able to ride without it dying out every other time i come to a stop, or the throttle hesitating. Like i said, she runs amazing 80% of the time!

The idle jet is sending fuel. I pulled the filter and watched it.

If you haven't already I would next give the carb a very good cleaning. Put it back together and test it out. If no change start looking for air leaks. Very important to do only one thing at a time checking your results after each. I'm no pro just a back yard wrench. Hope this helps.

I get an odd cough too once in a blue moon, so I will be watching this thread for a fixable outcome.

First, put 2 oz of Gumout fuel injector cleaner in 1 full tank of gas. Test ride for maybe 50 miles. If that does not help ya got some work to do. Pull the carb off. Clean, reassemble and check float level. Double check vacuum diaphragm for cracks. Put the 46 jet back in. 2 1/2 turn out on the mixture screw if factory. Screw it out 2 3/4 turn, test ride. If it still coughs, screw out another 1/8 to 1/4 turn. A 48 slow jet is way too rich for stock mufflers. I have a carbed 96 incher with V&H slipons and run a 46 slow jet.

Intake leak.

I agree with fxdlx every time my shovel would start to cough like that 9 out of 10 it was an intake leak.

I`m thinking there is some crud in the needle and seat area, causing the float bowl to overflow, dumping the raw gas into the throat of the carb.

Disassemble the carb and clean it thoroughly, and replace the fuel lines, also replace the intake seals while it is apart.

An older bike with low miles has sat around a lot. I went through that with my 2001 FXD when I first got it...What I did was to get a good kit with intake gaskets, some Seafoam, and carb/injector cleaner spray. Take the carb off, disassemble it, clean it with some Seafoam and an acid brush, spray carb/injector cleaner through the passages (watch the eyes), rebuild it with the kit (including the accelerator pump) and put the #46 jet back. Adjust the mixture two turns put it all back using the new gaskets. If it were me, I would also replace the intake to head gaskets...cheap insurance...and they maybe dried out and leaking.

This forum has a lot of good instructions and other resources for just about any kind of carburetor that bolts up to a Harley.. https://www.hdforums.com/forum/carburetor-related-60/

Was Dyno-jet carb kit installed, check with previous owner if you can. If it was, it would be good thing to take it back to stock #45 primary and a 190/195 needle. That cough is the transition from off idle to low speed (thank you EPA). Two ways to fix this. 1) install a Sportster needle, the p/n number escapes me right now and 2) install 2 #4 brass washers on the needle, this will raise the needle just a little bit to prevent the cough. I have the needle turned out just shy of 3 turns maybe just a little less and the idle set at 1000 rpm. This maintains oil pressure and voltage to 13.2-13.4v. Otherwise the battery won't get the charge, above 2000 rpm the voltage goes to 14.2 -14.8v. Google Joe Minton tuning the Keihn carb.

27094-88 Main needle ('88 XLH part)