Topic: No spark issue. Please help

[Jcold98]

Hello.

I have a 72 cb750k project with original wiring and I can’t  seem to get a spark out of my plugs. As of right now the engine is on a stand with only the bare minimum wiring in tact. I have a new dyna s ignition as well as new dyna coils. I have 12 volts going to the black wire of the coils as well as the skinny red wire powering the ignition. Wires from the ignition (blue & yellow) are connected to the (yellow and yellow) wires of the dyna coils.  The engine is grounded to the battery (-). And I have a hot wire running from the battery (+) to the starter post of the solenoid. Starter sounds fine and is moving the little sprocket like I believe it should be. I have a plug out and against the engine case and im looking for spark as I turn the starter on. One thing I have noticed, the coils are getting super hot just from me hitting the starter.

Am I missing something? Is there something wrong with my coils? Do the coils need to be grounded? Or not grounded? And I testing the wrong way? 

Thank you for any help.

[TwoTired]

The Dyna-s leaves the coils on pretty much all the time.  They heat up in ratio to the coil primary resistance.  3 ohm coils draw more than 5 ohm coils, so they will heat up more.

The only time the Dyna turn the coil off is during firing, which is about 20 -40 degrees of crank rotation, and only when the crank is turning.  At all other times the coils draw power.

The plugs should fire in pairs, and it needs the mated pair installed to fire along with the removed one you are examining.  It uses the head metal to make an electrical connection with its mate.

The coils do NOT need to be grounded.  The coil windings, both primary and secondary, are isolated from case or mounting brackets.

I can't speak toward why your Dyna-s trigger wouldn't function.  Certainly a new one should, though there have been many reported failures of ones that have seen service.  But, that is usually limited to a single coil output (2 cylinders dead).

Cheers,

[calj737]

Is the engine painted and thus you are not getting either the battery NEG or spark plug (extracted) a clean, proper ground?

[Jcold98]

The coils I have a rated at 5 ohms, but I didnt know they stay in the entire time. I had just noticed they got burn your hand hot when I fired up the starter.

And the engine is not painted, I figured the ground would be ok since I have the starter working?

Thank for the all your help guys! Its all super appreciated

[TwoTired]

Standard points only keep the coils on for ~190 degrees of crank rotation.  So, only one coil would get warm when the engine is stopped.
 During run, the Dyna turns coils on for ~275 degrees of crank rotation.  When stopped the coil remain on, as long as power is applied.
12 volts and 5 Ohms yields a 2.4 Amp draw, or 28.8 watts to dissipate inside each coil when they are on simultaneously.  This is 98.2 BTUs per coil, if my conversion tables are correct.

Back when Easy bake ovens were still around, they would bake cupcakes at 350 F, using a 60 watt incandescent bulb.  So, you should be able to bake a cake with two coils in the place of that bulb in the oven.   This info might come in handy when the apocalypse comes.

Cheers,

[scottly]

I had just noticed they got burn your hand hot when I fired up the starter.

And the engine is not painted, I figured the ground would be ok since I have the starter working?

"Burn your hand hot" only when the starter is running??