Topic: No spark.. Please help?

[racemx51]

Okay guys so before my bike came apart it ran. Long story short its back together but Im not getting spark. There is power going to the coil. but nothing past it. Obviously, Im going to try another coil I have because obviously its pointing towards the coil being junk. But its just the fact it ran coming apart, why would the coil just go bad like that...

But my real question is, what grounds these things? It seems that the coils on these bikes ground just directly to the frame when bolting then up? This is my first CB I build but Ive got a lot of bike experience...

What do you guys say? Im guessing that coil is just no good...

[OldSchool_IsCool]

Welcome MX!

Which year and model do you have?

Typically, you should have 12v on the black/white wire when you have a good battery in, key on and kill switch set to run.  Do you indeed have 12v there?

The blue and yellow wires run down to the points (assuming you have points).  the points provide the path to ground for the coils.  the coil with the blue wire connect to plugs 1&4, the yellow to 2&3

[MoMo]

Coils rarely if ever go bad, you need to provide the ground path by cleaning the points with a fine emery/point file, some electrical contact cleaner and compressed air...Larry

[racemx51]

Old school, its a 73 CB 750.. I'll go for the points next and week where I get.. Any other ideas other than that? Or tips? This is my first street bike Ive built. Ive raced motocross since I was 7 and have been a Professional since 2003 and run a body shop, and have a lot of mechanical experience...BUT...Wiring, not my thing... I can honestly say Id rather rebuild five motors than wire one bike. I hate it... Im finding the wiring on these bikes to be a bit more complex than they seem to need to be? Is that just me? 

[OldSchool_IsCool]

Just think of wiring like you would plumbing and you'll do just fine!

[Danno]

sounds like your coil trigger wires could be grounde take a continuity tester and make sure there is no continuity between the little points screws and the ground when they are open if not that is your problem

[racemx51]

Checked my points and dont see anything wrong there. But only looked at them...What should I do now. Once again I know Im sounding like an idiot here, I promise Im not...But wiring isnt my thing at all.. Im seeing two points, now I should check what I have for power going through them?

Im used to dirt bikes and painting, not wiring 

[TwoTired]

You should have 12V at the B/W connections to the coils.
The Blue and Yellow wires connect coils to the points, which provide a ground when closed.

With the points closed you will see ground on the Blue and Yellow wires alternately, depending on points cam position.

The coil charges up when the points are closed and fire the plugs as the points open.