How do I check spark plug wires for Olms when they are still connected to the coil? I know 1 way is to remove the wires from plug & coil to test it but can I do it while its connected to the coil?

Reason I ask is that I think there might be something wrong with 1 of my spark plug wires but my coil is hidden & kind of pain in the a$$ to get to. Id like to avoid removing the wire if possible. Any help is appreciated.

 

You don't necessarily need to remove the entire wire, but you should at least remove the cap end from the coil. If I remember correctly, it should be something like 50 milliamps?

 

I'm trying to test my memory... I think your resistance should be lower than 200 ohms per inch. Better quality wires have less resistance.

 

the correct method is to remove the wire from the coil and spark plug. measure the length of wire, and write it down than ohms the wire for its resistance. divide the total length of the plug wire by the ohms reading the final number will give you the numbered resistance per foot of that wire. compare it to the service manual spec and if it bad replace it. just checked to known good ones the shorter one 2.230k ohms and longer one 5.210k ohms.

 

Yes, I used an old rule of thumb method for vehicles 20+ years ago. The correct way to do it is check your service manual. My wife's 06 sportster book says 5030-13,733 ohms for a 20" length.
Used to take a spray bottle of water to them in the dark to check them as well, while running.
How long are your wires target?

 

7.5 & 18 inches.

 

But is there any way to check them without uncaping them from the coil? My coil is in front of the rear tire so it'll be 1. a pain in the a$$ to get to and 2. I wouldn't be able to get both ends on the voltage reader without removing the entire wire.

If I gotta do it that way, then ill do it but just trying to find out if there is any other way to get a reading. Thanks for the input and help!

 

I suppose you could get a hei (high energy ignition) spark checker from your local auto parts store. It looks like a spark plug with a small clamp welded or brazed on the body. But that method is only used for a no start.
What is you original problem? No start? Skipping?
What are you working on?
I really don't think there's a way to prperly test wires without removing them. I suppose if you had an oscilloscope and knew how to hook it up/read it you could do that. You would still need access to the coil.
Just be very careful removing your wires. They are easily damaged and can be difficult after years of being in place.

 

I moved my coil to under my oil bag & had to make extended spark plug wires. After taking the bike for a test ride it felt like it was only running on 1 cylinder with an occaisonal kick from both.

I get home, remove the rear spark plug & bike doesn't start. I re-install rear plug & remove the front plug. Bike started right up. I compare both spark plugs & the front 1 is black as night and the rear looks normal. Since I didn't have this problem before, I'm thinking its got to be something wrong with the plug wire for the front.

Thoughts / ideas? & thanks for the help!

 

like clutch 767 said get a HEI spark checker at napa store or see if a garage around has one u can use . hook it up and start the bike, you can watch the spark to see if it jumps the gap and than switch cylinders. you will see which one is bad, possible a bad coil also. if the spark is present in both cylinders ,
you had better check the compression in both cylinders.