Keihin accelerator nozzle leak while idling : V-Twin Forum: Harley Davidson Forums

Woody05RK · 08-04-2008, 06:06 PM

I have a stock keihin carb on my 1983 fltc that leaks fuel from the accelerator nozzle while it's idling. I have cleaned the carb from top to bottom. The float level is correct and the inlet needle works fine. I took the accelerator nozzle out along with the needle below it. Is there supposed to be any type of spring above the needle or an o-ring below it? My service manual doesn't show these as seperate items. It's all part of the bowl assembly according to HD. The fuel spurts from the nozzle and pools in the throat of the carb. After a while it saturates the foam filter and leaks out of the ham can onto everything. Any suggestons would be appreciated. I don't want to replace the carb with a cv. It's a 99% stock bike and i'd like to keep it that way if possible.

nmaineron · 08-06-2008, 05:16 PM

There are a few things that you can check Woody.First make sure that your throttle cable is not so tight that it is pushing on the plunger.You could also have dirt or a tear in the diaphragm on the bottom of the plunger.It is in the little disc like part of your carb on the bottom.This acts like a check valve and you may be getting flow through it from your bowl.The natural flow of air by the nozzle will act like a syphon,similar to sucking on a hose to siphon from one container to another,once it starts it won't stop.Try shutting the petcock also,the fuel is trying to maintain the same level that is in the tank.Good luck,Ron

Woody05RK · 08-06-2008, 06:29 PM

The diaphragm looks good to me. There was a pile of dirt on top of it. The rubber seal on the rod was installed upside down from the previous owner or last wrench. The throttle cables are adjusted with the proper slack. Since the boot was upside down I have my suspicions that there may be something missing under the accelerator jet. I can't see how just a needle dropped down below the acc. nozzle would seal while the motor is vibrating up and down as hard as it does. It seems like it would aid in making it leak. If the motor held perfecly still maybe it would work, but that won't happen. The shop manual doesn't show any of these parts just like it doesn't show the slow jet adjustment buried under the plug. It just doesn't seem like a very postive check valve to me. If anyone has a complete parts breakdown or a link to one, that would be very helpful. If I remember right the same carb was used from 1982 to 89 or so. Thanks for the help.

LoneEagle964 · 08-06-2008, 10:52 PM

not sure if this will help but all I could find
http://www.bikebandit.com/harley-dav...c-1983/o/m1240

LoneEagle

nmaineron · 08-07-2008, 08:02 PM

Woody,I was just looking at an old manual,the only thing that is in the diaphragm chamber is the diaphragm and a spring that sits below it in the bowl.

Sorry I have no way of scanning and posting it,I was looking in a 1978 1/2 to 1982 manual.

I believe the Keihan goes back to the mid seventies with a few mods thru the years.Ron

Woody05RK · 08-12-2008, 06:40 PM

Thanks for the help guys. I think I may have stumbled onto the problem. I went ahead and soaked the carb in cleaner for good measure and put in a rebuild kit. The pilot jet was covered in a goober of rtv. I peeled it out and found the pilot screw out 4 3/4 turns. I turned it in to 2 1/2 and got a face full of backfire. Didn't quite singe the eyebrows, but it was close. It finally ran good around 3 1/4 turns out. Any less and it would pop like mad. The only thing I can figure is the air bleed hole behind the acc nozzle may have been moving too much air and pulling a vacuum on the acc nozzle making it dribble. 3 1/4 turns out seems a little much to me. I don't know if the pilot jet has been changed from stock. Next time i'm in there i'll have to check. One again, thanks for the help. This is a great site.