Hey, all I've poured over hours of info here and am still not sure what's wrong. I've got an 02 1200 Sportster with 9k miles just picked it up two weeks ago. All stock motor, carb, and exhaust. She starts and idles beautifully but then when you go to blip the throttle while idling she'll hesitate and pop through the carb. Same thing happens when coming to a stop while riding as well. Also while riding, in the lower gears (1-3) while trying to maintain throttle the bike coughs and bucks with a hesitation. But if you are getting on the throttle there's no problems and she picks up well and the problem seems to not happen in 4th or 5th gear (the bucking/coughing that is) but she'll pop through the carb still. So I read on here that I could spray some wd40 around the intakes to check for leaks. So I sprayed both intakes tubes and the back side of the carb and each time my idle dropped significantly. Does this indicate an air leak? Isn't the rpm's supposed to go up? So is my problem the leak? Or could it be a gummed up carb and leak? I've ran two tanks with fresh gas and SeaFoam but no changes. I'll turn a mean wrench but I'm uncomfortable just tearing in to this. Any suggestions, thoughts, tips or tricks welcome. Thanks to all for your time.

 

Update. Checked both plugs. They're both white(lean) leading me to believe it is a leak as the root of the issues. Wouldn't it leaking, pulling in air, lean out the mixture? Is it to horrible a process to remove the carb and replace the seals/gaskets?

 

Yes it would. What is the jetting on the carburetor? Does it have the ignition in the nose cone?

 

I would start with replacing the intake seals. WD-40 probably wont make the idle flare up like carb cleaner or brake clean. My 05 was doing the same thing. I still get a carb fart from time to time but it has taught me not to be a throttle blipper.

 

Jetting is all stock. Talked to the old owner. The carb has never been played with. And as far as I can tell the ignition is attached to the front of the frame underneath the tank. Guess I don't understand the cone reference? And I just tried the spray thing again with starting fluid. No uptick in RPM's but it bogged down like the WD40?

 

I don't remember the year group (late '90s - early 2000s) but for several years HD put the ignition module for some XLs in the nose cone. On the right sight under "5 Speed" medallion right above where the mid-controls brake is. Well this had problems with overheating. I had a '99 883 that ran great until it got hot, it would then shut down. Happened to me a few times until I figured it out. Usually I would be able to coast into a gas station and get ice and pour over the cone until it cooled off and then went straight home. One time my wife had to bring me a bag of ice and we kept putting it on until it cooled off enough to start it and get home.

Best answer is to find a SE ignition module. Replaced it and never had another problem out of it.

My '01 1200c did not have the module in the nose cone and I never had a issue.

Here is a link to replacing it and they talk about backfiring and missing in it.

http://www.hotbikeweb.com/screamin-e...kfire/?image=0

 

Update: (Sorry it took so long) Replaced the intake gaskets, carb boot, cleaned the carb out, shimmed the needle, upped the main jet, new plugs/wires, replaced old vacuum lines and fresh fluids all around and she runs like a champ after setting the mixture screw=)