I have an 04 Deuce, carburated. I am the second owner. The best way I can describe the problem is that the engine stumbles when, while riding, the throttle is openned about 1/8 to 1/4. It's not constant, just momentary. If I crack the throttle open wider than 1/4 it runs strong. This goes on for about the first 15 minutes of riding.

A little background. The PO installed (or had installed) vance&hines pipes and a K&N air filter. Claimed the dealer did the work along with rejetting. At the beginning of the riding season (here in CT) the engine just quit as if out of gas. I pulled the tank, fuel valve and carb. Fuel valve has integrated screen which was gunked up so I cleaned it. I removed the float bowl from the carb and it appeared that whoever "jetted" it used silicone sealer on the bowl gasket. I unclogged/cleaned the internals. Noticed that the main jet is a #190, this is standard for this bike, this carb according to the manual. I could not make out the number on the pilot jet but did not remove it to look either. The standard pilot is a #45 but again, I do not know what is in there. After cleaning and reassembling I also removed the air-screw plug and adjusted the screw to 2 and 1/2 turns from lightly seated. After reassembling the now-clean fuel screen /valve and tank and replacing the carb with a new manifold rubber gasket the engine ran great at any throttle openning.

It seemed to run poorly under light throttle operation all of the sudden. Bad gas maybe? Does this sound like a clogged pilot jet or something else?

 

it sounds like your idle jet is dirty, it is the first to clog up when you get gunk in the carb.. there should be a drain screw in the bottom of your fuel bowl, open it and let fresh fuel flush thru.. if that doesnt do it, you are going t ohave to remove carb,take it apart and clean.or have it done..it isnt taking longer to warm up because its cold out is it?? you would be amazed how many times i have heard "my bike is taking twice as long to warm up"when it is 30 deg out... couple times a week in when its cold out for 13 years

 

My $.02
The carb needs a proper cleaning. Remove the slide, bowl, both jets, idle mixture screw etc.. and spray out all the passage ways in the carb. You might want to get new jets, anyone who uses silicone might try drilling out a jet. I'd recommend a 190 main and a 48 pilot or a 50 when its painfully cold riding.

 

That's good advice. It is not the ambient temp as this started while it was still in the 70's around here. It was almost 60 the last time I rode so I will take it apart over the winter and clean it. I did not think about the drilling thing. I have read about a drill procedure but do not recall the specifics. What should I look for? Could they have drilled the slide and maybe the jets too? Jets are cheap so no issue replacing both. Thanks for the input.

 

I'd look for an intake leak as well.

I'm a big fan of the CV carb and I use this mod:

http://www.nightrider.com/biketech/hd_cv_mods.htm

troubleshooting here:

http://www.nightrider.com/biketech/c...leshooting.htm

drilling the slide, changes it's reponse, which works with the n65c needle.
for comparo my evo bagger is 42/165/n65c drilled chamfered slide.
44 mpg @65 MPH, great performance

Mike