Erratic idle

[VintageTwin]

Description: Would start right up..but would rough idle at a stop light

Wellll.....I think I'll go and get me a new tattoo...take my 'ol Harley for a three day cruise...Oops...Hey!.. didn't see you standing there. My machine was running poorly last week. Would start right up..but would rough idle at a stop light. I had to pay attention to the throttle, which is a major distraction. It would occasionally skip a beat. Even died once at a traffic light and I heard a snicker from someone about two cars back, like a "Hardly-Ableson" guffaw. Embarassing. Looked at a whole litney of troubleshooting reasons in the service manuals (i.e; bad coil, bad condenser, plugged air vent hole in the Linkert, etc.) [That vent hole is under the boss of the high speed needle. Held the squared end of a plastic tube against the hole and sucked. Got the taste of gas fumes. Nope not clogged.] Finally went to the easiest source of the problem and checked the gap between the points. Put a 0.022" feeler blade betwixt 'em and was able to rack the blade. That ain't right! Re-set the points to 0.022" and blasted the spark plugs for good measure. The machine started right up and ran poifectly smooth. Idled without skipping a beat. Problem solved. Happy Jack. If you build the motors right, these Pans are as simple to maintain as a Model A Ford. One coil, one God (of your choice, of course), one set of points. Note: You can make a dual points Pan, a single points Pan, by changing back to the '36-'60 square coil, and use a '47-'60 single points timer. Use the "Front" timing mark on the flywheel to set the timing, and not the "back" stamped timing mark on the flywheel.

[BIGAL]

might be sucking some air. take some wd40 and spray it around the intake while its running. If the idel changes its sucking
air

[Cotten]

The WD-40 trick only tells you when you have a bodacious leak. A tiny one can slip by and give you any kind of grief from uneven plug burn to holes in your pistons.

The only way to be certain, or figure out where and how much it leaks it to pressure test the manifold with dishsoap: http://virtualindian.org/11techleaktest.html

[VintageTwin]

How about kerosene in a spray bottle? I watched "Sherm" (the Oceanside dealer) spray kerosene on my running Sportster's intake manifold when he was looking for a leak. I axed him why and he said, "I use kerosene, because if there is a leak, the motor will still run, but it will falter when it sucks up the kerosene." There wasn't a leak...I drove it home and removed the carburetor. I had painted the cap "rim" of my gas tank, and a strip of paint had been sheared off and fell into the tank and lodged into the gas intake hole in my Tillotson..starving the motor for fuel.....Ha-Ha-Ho-Ho-Hee-Hee, to the funny farm, where life is easy and I'll be safe....my lesson to never paint the top rim of a gas tank filler neck.

[dirtpandan58]

I heard a long time ago about leak detecting with propane.
Unscrew the tip off of a propane torch and attach a length of hose to the part you took the hose from.
Now you can point the hose where you want it a little easier without spraying fuel all over you bike.
Never had to try it,but it made sense to me and I thought I'd pass it on.

Dirt