My '82 FLT 1340 started cutting off going down the road. I would see the tach drop to zero, and figured out if I reached down and cut the ignition switch off and back on, it would come back to life (with the cool associated backfire occasionally!). I pulled out the ignition switch and cleaned / rewired all the contacts but still had the problem. It's gotten more frequent and I actually have no spark at all right now - at least that happened in the garage, since my last ride. Something told me it wasn't the ignition switch, but I'm still not sure. What I found was that the ignition module is a Dyna S, and I went through their test procedures and there is no change in voltage on the negative side of the coil as the engine is rotated like there should be. I pulled the sparkplugs out to make rotating the engine easier and found the electrode is burnt almost to a point! They were fine a few months ago.

Any comments, ideas, suggestion? Kind of a weird situation, just wondering if anybody else has seen anything like this. A new module is about an HD (Hundred Dollars, lol - I guess they earn their name).

 

I should have added that there IS voltage to the coil and ignition module, so the ignition switch is not at fault - at least as I'm testing it in the garage - not sure what happens going down the road. Dynatek's procedure for testing the module is to attach a voltmeter to the negative side of the coil, and ground it to the chassis, then rotate the engine with the ignition switch on, and observe a voltage change - mine is staying at 12.4V all the time, barely varies at all.

 

Not uncommon for the Dyna-S to fail...especially if you are running a low ohm Coil!
The S seems to prefer a Points coil.
Or maybe that is a coincidental experience for me...
But, I'll continue to use My Dyna-S with a points coil.

 

Coil checks 3.6. Maybe I'll get a 5 while Im at it. KaChing! HD!

 

the directions tell you dyna S has to be used with a 5 ohm coil NOT a 3 ohm coil and carbon resistor wires not the solid cable type point wires that you had or still have

 

3 ohm burns hotter, 5 ohm lasts longer.

 

Do you think that would account for my burnt up plugs? I haven't had the bike that long, or put that many miles on it, so I don't really know how fast it burned up the plugs. They seemed fine just a few hundred miles ago. (???)

 

I don't know that, but I've had several bikes over the years with Dyna S ignitions and have always run 5 ohm coils without a problem.

I checked the Dyna S instruction sheet just now and it specifies 3 ohm for race application and minimum 4 ohm to 5 ohm for street. So there you go!

 

Well, I ain't racin'! So, I guess I'm looking for a coil or two now as well....HD!!

I'm a little confused on the coils too....does it matter whether the coil says it is to be used with points/condenser? Will those coils work just as well with the electronic module?

 

Consider yours a contactless points system. And since Dyna S are dual fire (you only have one half moon contact in your nose cone?) you can run just one coil if you choose.