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...

 

[modifiedamerican]

this doesnt help u at all but im the same boat u are. except with my kz750. i still cant figure out it! i got power going to everything, everything is brand new but no spark. im taking it to a mechanic next week. :/

 

[VonYinzer]

What bike is it?

 

[Swapmeet Louie]

Do you have power at the points? If it has them....? Coils are isolated. I.e not grounded through the body of the coil.

 

[teazer]

To add to what Louie said, the coil grounds through the points and condensers . Think of the power flowing from the battery to switch to kill switch to coli to points and condenser to ground.

When the points are closed there is almost no voltage at the coil because all those nasty little electrons are rushing through the points to ground taking the easy way. So that can be deceptive. Open the points and see if you have 12v at the coil now.

Most likely issue is a bad connection or the points not making contact or shorting to ground. Check the wiring

 

[racemx51]

Vonyinzer, its a 73 CB 750... I went through the wiring pretty closely today but havent checks the points yet which is something that Im planning to do... If I put the new coils on and nothing, I think I'll start with running new wires and see if that does anything. But I did have power all the way to the coils so it still kind of fools me..

 

[Frankmowthelawn]

Put a little piece of cardboard between the points and turn the ignition on. There should be 12 volts across the points if everything is OK there. Are the plug wires in the boots at the sparkplugs solidly? Did you make sure you timed the ignition on the compression stroke? It won't run if not and the timing marks come up twice for each time the engine fires. It's an easy thing to do.

FMTL

 

[born2expire]

condenser....

 

[racemx51]

I never took anything in the actual motor apart because it was running before I ripped the bike apart. I'll try the points thing and see what happens with that I guess... I'll let you boys know.. Thanks for the help guys...