Bike wouldn't start the other day, ('99 Dyna Big Twin) sounded like it was only firing on one cylinder, and I finally got around to running the diagnostics. The HD manual is indispensible for this type of troubleshooting.

No spark to the front cylinder. Both wires/plugs checked.

I discovered the ignition coil has higher than spec resistance between the secondary windings (bad). I need a replacement.

I'm running stock w/ V&H pipes, SE air cleaner, and a mild HD 203 cam and stock plugs.

Comments on HD stock, HD SE, Accell, other? Should I go stock or single fire?

Thanks,
Kurt

 

Just replaced my entire ignition system on my '86 FLTC. Turned out my issue was in the module.

For a coil I went with the SE OEM only because they didn't have the original equipment coil.

I didn't find the coil made a difference and it turned out to not be the problem.

Dual fire requires more than just a coil change, you'll need an ignition module that is designed for this purpose.

I found the aftermarket module I installed (Crane HI4E) gave me a small performance gain. It controls the spark (using multi-spark setting), it has adjustable advance curves for quicker acceleration, and it has a rev limiter that allows you to set the limiter quite a bit higher than stock, even a little higher gives you a bit higher top speed. This module also gives me the ability to use it with a stock coil, or add a dual coil system for dual fire.

I also found that it altered the sound of my EVO by increasing the heat and length of the spark. It gave me much faster "roll on" response giving me quicker acceleration and I gained almost 17 MPH in top speed.

Keep in mind just because the coil is not sparking doesn't mean it's not working, it could be a series of items that control the coil that's preventing it from sparking.

Most coils range from 2 to 3 ohms when measuring the secondary, if you'd don't have the right meter, or setting you can believe the coil is reading wrong and bad. The coil I replaced show 3.1 Ohms and changed when I heated it to test for running temperature break down. Heated the range changed to outside of specs. But in the end it was the Ignition module not triggering the coil. Also the timing and spark are controlled by the cam sensor and this can work under start up conditions and not work as it heats up. There are ways to check it but after replacing everything a step at a time all the way from the least expensive up to the most expensive part of the ignition I now have a new system from top to bottom and know a lot more about the system.

 

Thanks JonnyC,

The HD manual says the coil secondary (there isn't a primary) should read between 5,500 - 7,500 ohm. My Craftsman digital meter read 11.53 ohms at 20K meter setting, and 11.5 at the 200k setting. I am not getting any trouble codes when I jump the 1 and 2 wires on the data link. According to the manual I should see a 55 code for the ignition module if it failed.

I think I'll stick to the stock coil, and look into the ignition module. Seems like a pretty good gain for the money.

Thanks again,
Kurt