Single Spark?

[Steadymule]

Hello, this is my first post on the site. Normally any question I would have has already been answered for me but I am at a loss right now. I am currently finishing my first build. Its a 1981 CB750k. Right now it's all back together and everything is looking good. M.unit is wired up and everything seems to be in order. The issue I am having is getting a continuous spark. Right now when i go to start the bike it turns over and everything is moving like it should. But when i check the spark, their is only one initial spark right when the starter is pressed and then thats all she wrote. I have read that people have issues with no spark or weak spark and its related to the pulse generator or the amplifier. I just can't seem to figure out if thats what is wrong with this particular scenario or if it is something different. Any advice would be extremely helpful.

 

[pidjones]

Check that your coils are grounded through the ballast resistor. Often they ground through the start switch, then when you release ground through a "ballast" resistor that cuts the running current down.

 

[cxman]

make sure that you have power to the coils after the first spark and that they are not losing 12 power

check your ignitors are staying powered

check your pulse generators for proper resistance

 

[teazer]

That suggests that power to the coils or ignitors is coming from the starter button and not from its own switched 12v supply. Check wiring to/from the starter button and to the coils and ignitors

 

[Sonreir]

That suggests that power to the coils or ignitors is coming from the starter button and not from its own switched 12v supply. Check wiring to/from the starter button and to the coils and ignitors

I have a similar theory. The DOHCs have a headlight cutout when you press the start button. Possible that the coils are getting power from the headlight feed and when you press the start button, you're losing power to the coils.