Hey guys I’m working on a 2004 electraglide glide standard carb bike. There’s this weird snapping sound that sounds like and electrical spark jumping contact. I’ve been up and down this bike trying to find the source. I’m trying to test the coil right now and can’t find a procedure anywhere. I found the specs in the book but what Ive found seems off to me. The resistance checks on the primary and secondary side are within spec, but what’s strange is that there’s continuity between all the contacts. 3 three electrical contacts (power in, front cyl, rear cyl) all have approx 3 ohms resistance. when going to the secondary side, the plug wire tower to electrical connection has about 6k resistance (5500-7500 is spec). Weird thing is both plug wire towers have the same resistance to all 3 electrical connections (power in, front cyl, rear cyl). Isn’t this supposed to basically be two separate coils (front and rear)? Am I missing something here?

 

Coil primary is only 1/2 ohm. A cheap ohm meter will have trouble measuring the difference between the pins. Test leads are probably 2 1/2 ohms.

If you have some kind of arcing, you'd likely have a miss.. If you don't look elsewhere for the noise.

 

Doesn’t seem to be a miss. Meter is a digital fluke meter. Bike runs fine except for that snap sound. When lightly blipping the throttle is when it snaps or when under load. It’s one single snap. When going up a hill it’s multiple snaps but they’re spaced out. Compression is good, leakdown is good, I’ve tried a different carb and a different intake. New plugs, tried another set of plug wires, no vacuum leaks around carb/intake, I’m at a loss. It was Running poorly is why all the testing. It’s Running good now except that damn snap lol. I’ll see if I can get it on video tonight

 

Sparks are easier to find in the dark.

 

Tried that too. Tank is off I’m running it off a remote fuel bottle. Lights off and no spark that I can see

 

It should be noted that I’m not sure that its electrical. It sounds like an electrical arc, and I’ve been top to bottom on the mechanical side.

 

Even with a good meter, the leads will screw you over unless you got to a specific meter for measuring lower resistance. Probe tips can be ohmic..

I would guess a head gasket, exhaust leak or something loose. Are they any mods to this bike? Mileage?

You can have a high pressure leak that won't show up on a compression test cuz it takes more than a few hundred psi to pop.. Q-tip around HG to to see if it's leaking.

Baggers have a bunch of heat shields that can slip and tap places.. Brake pedal pivot. Tranny pipe mount can be loose or cracked. Pipe bracket on starter. Left exhaust hitting primary. Pulley bolts. Front brake hose can tap the front fender. Rear header pipes crack. Front motor mounts go bad.

 

Bike has an S&S big bore 98 with 570 Gear drive cams in it. I assumed since compression was good that head gasket would be. 158/159 compression. 2%/9% leak down. What I don’t get is it’s literally just the one snap. Sounds as if coming from the carburetor area. Times perfectly with throttle opening and spray from accelerator pump. About 58000 miles on it. Probably less than 5 on the big bore

 

is it a stock hd coil??

coils or better word transformer are made in diff forms. you may have what is called an auto transformer. the old magnetic coupled transformer is disappearing with the advent of computer control. with the auto transformer, primary flows through the secondary.
of note is that on newer hd's, always have a ground path for the high tension when testing out the cyl as the high tension can do damage to the coil winding and module.
do you have a friend with an o-scope?? the wave form will show the loss and which cyl. i had one coil on an ironhead that would snap and it turned out to be a hairline crack in the case and all the wiring was good.

 

Stock coil. No scope.