Fires on one cylinder

[clayton]

My Sportster fires on the front cylinder and not the rear, spark plugs are okay when I switch the wires around the rear cylinder will fire and not the front I am assuming I have a bad coil could this be the ignition. The bike is a 1991 883, I am not getting spark from the left post on the coil.

[14Frisco]

Assuming it's the stock ignition, it's a dual-fire ignition so if you get spark on one the ignition is probably ok.  Depending on how you "switched the wires around" - whether you eliminated the wire itself being the problem, or not - it could be the spark-plug wire or the coil.

You can measure the coil:
- ignition coil primary winding side should have a resistance between 2.5 - 3.1 ohms
- ignition coil secondary winding side should have a resistance between 10,000 - 12,500 ohms

[afghanlander]

I have an 01 883 and had the same problem.  Mine was a plug wire with the end burned off under the boot but inside the coil.  Couldn't see it until I pulled the wire.