Topic: CB550 - No spark

[Johnny5]

I got a 75 CB550 that isnt getting spark. I tested the coils and they are good. Power is getting from the points to the coils but only sometimes and that sometimes is weird: It's only when the large green ground that is connected to the frame by the coils is disconnected. Then there is power to the coils. If I ground that to the frame, then no power to the coils.

The battery is good. Im just not finding something that is connected wrong. And suggestions on what it could be?

[Lumbee]

Not familiar with the green wiring you are referring to...I was thinking the coils are grounded to the frame just by being connect to it. You could run power directly from the battery to the coils to bypass any wiring. I've done that before when troubleshooting issues like this. It rules out anything between the coils and the battery.

[Johnny5]

Not familiar with the green wiring you are referring to...I was thinking the coils are grounded to the frame just by being connect to it. You could run power directly from the battery to the coils to bypass any wiring. I've done that before when troubleshooting issues like this. It rules out anything between the coils and the battery.

The green wire attaches to the place where the coils are grounded to the frame. On the bolt on the front end of the coil bracket.

[TwoTired]

I got a 75 CB550 that isnt getting spark. I tested the coils and they are good. Power is getting from the points to the coils ...

What the h...

The points make a connection to the engine case, which should ultimately connect to the battery NEG terminal.

Power from the Battery POS terminal is provided to the coils via the Blk/Wht connection.  The Blue and Yellow wires connect to the points.  The closure of the points makes the coil store energy, which it dumps as spark when the points open.

The coil's mounts are NOT ground for the coils, and have no effect on or have any electrical connection to the coil internal windings or operation.

Cheers,

[Johnny5]

I got a 75 CB550 that isnt getting spark. I tested the coils and they are good. Power is getting from the points to the coils ...

What the h...

The points make a connection to the engine case, which should ultimately connect to the battery NEG terminal.

Power from the Battery POS terminal is provided to the coils via the Blk/Wht connection.  The Blue and Yellow wires connect to the points.  The closure of the points makes the coil store energy, which it dumps as spark when the points open.

The coil's mounts are NOT ground for the coils, and have no effect on or have any electrical connection to the coil internal windings or operation.

Cheers,

Sorry, I screwed up what I meant to say. Power isnt coming from the points, but Im getting electrical flow all the way to the coils. When the larger green wire with the loop on it is grounded, the electrical flow to the coils is gone. When the green wire isnt touching anything, power is getting to the coils. It's almost like something is backwards, but I cant find it.

This is a friend's bike Im trying to get running and Im not really familiar with the 550's.

[Johnny5]

Ah, after researching a bit, I think there's an issue with the kill switch not feeding current to the coils. I'll check it out tomorrow. Thanks,

[TwoTired]

Sounds like you have grounding issues.  Lack of grounds can make voltages appear in odd places.  However, that is different than power, which is voltage AND current.

Why not make the connections corresponding to the Honda wire diagram?  Or, tell us what is different than how the Honda wire diagram depicts/defines.

Cheers,

[Johnny5]

Sounds like you have grounding issues.  Lack of grounds can make voltages appear in odd places.  However, that is different than power which is voltage AND current.

Why not make the connections corresponding to the Honda wire diagram?  Or, tell us what is different than how the Honda wire diagram depicts/defines.

Cheers,

Yep, that's the plan. I didnt have a diagram until this evening and the bike's not at my house. Everything looked normal. Im thinking there's a connection that's corroded or something.

[chopped550]

I got a 75 CB550 that isnt getting spark. I tested the coils and they are good. Power is getting from the points to the coils ...

What the h...

The points make a connection to the engine case, which should ultimately connect to the battery NEG terminal.

Power from the Battery POS terminal is provided to the coils via the Blk/Wht connection.  The Blue and Yellow wires connect to the points.  The closure of the points makes the coil store energy, which it dumps as spark when the points open.

The coil's mounts are NOT ground for the coils, and have no effect on or have any electrical connection to the coil internal windings or operation.

Cheers,

Sorry, I screwed up what I meant to say. Power isnt coming from the points, but Im getting electrical flow all the way to the coils. When the larger green wire with the loop on it is grounded, the electrical flow to the coils is gone. When the green wire isnt touching anything, power is getting to the coils. It's almost like something is backwards, but I cant find it.

This is a friend's bike Im trying to get running and Im not really familiar with the 550's.

power shouldn't be coming FROM the points, it should be going TO the points. On my 550, I have a yellow and a blue wire, and two black with white chasers. Yellow and blue go to the points, the other two are power.