Topic: Help with CB550F wiring please

[HawaiiMike]

I'm getting close to completion on my '76 CB550F.  Engine removed, repainted, rebored.  Frame painted, front brake rebuilt, new back tire, etc. etc.  It has a new battery that I trickle charged for about 8 hours.

I spent a few hours cleaning the connections on the wiring harness, putting it on the bike and hooking the wires up.  When I turn the key to the running position, no juice.  When I turn it to "park" the tail light comes on.  That's it.

My guess is that the ground wire at the coil is not getting an adequate connection to the frame.  I scraped the paint off the frame before bolting the wire up with the coil mount.  However I don't know why nothing else would work on the bike except that one light bulb.

In the headlight shell there are two unused connections.  One is a brown wire, which I believe is supposed to be disconnected.  The other is the wire to the clutch safety switch (red/green I think) which I capped off.  My switch has been broken for awhile so I didn't put it on when I reassembled the bike.

Near the coils (that big bundle of wires that go into the black box), there's a green connector that's unused.  I think that's supposed to be left that way too, looking at the wiring diagram.

By the way, the electrical stuff was working when I disassembled the bike.

Any suggestions on how to tackle this?  I'd appreciate it.

[Lars]

Not an expert on this, but my first guess would also be the grounding. I believe you have another main ground cable from the battery to the frame. Checked that one - removed paint?

[Gordon]

Fuses?

[HawaiiMike]

The fuses are all good.  I bought extras just in case - I was worried they'd blow as soon as the battery was hooked up.

I just ran disconnected the ground wire at the coil and ran a wire from that directly to the negative side on the battery.  Still no lights except the tail light in the park position.

For now I'll charge the battery overnight (just in case) then wait and see what other suggestions show up on the forum.

Thanks, Mike

[Gordon]

You can eliminate or confirm the ignition switch as the problem by bypassing it.  Jump the Black to Red wire, and the Brown to Brown/white.  If the bike turns on, then the switch is the problem, if not then it's somewhere else. 

[Lars]

On the backside of the ignition key switch, there is a rubber part covering the cables. Take it gently off and inspect the cable connections to the switch, maybe bad soldering. However, as it worked before you stripped the bike, I would rather think you have a grounding problem og not got all of the wires correct or properly connected. What about the white assembly connectors (or what it is called behind the left side cover, are they all connected properly?

[HawaiiMike]

Thanks for the tips.  I trickle charged the battery overnight (although I don't think that's the problem) and will look at the ignition wiring this afternoon. 

That might be the issue.  When I first looked at the Honda, the ignition connector was smoking.  The owner had to resolder the wires because they had frayed.  It wasn't a great job.  Maybe some of those connections worked loose when I removed the harness from the bike.  I'll disconnect the ignition and try the wires at the harness.

If the ignition is not the problem I might need to learn how to use a multimeter.  The connectors behind the left side cover have all been cleaned and connected.

[HawaiiMike]

You can eliminate or confirm the ignition switch as the problem by bypassing it.  Jump the Black to Red wire, and the Brown to Brown/white.  If the bike turns on, then the switch is the problem, if not then it's somewhere else. 

Gordon, thanks for the tip!  The problem was with that five-pin connector from the harness to the ignition switch.  I disconnected it, ran wires as you suggested above and the lights came on.  Next, I cleaned up the connections and reinstalled the ignition switch.  Now we have power.

I put some gas in the carbs via a hose and funnel.  Tried starting it up, no luck.  Checked for spark and wasn't getting it on all cylinders.  Apparently the plug wires and the caps weren't connecting well.  Got a spark on all cylinders, still wouldn't fire up.

BTW the starter is not working - I was using the kickstarter.  That was another intermittent problem with the bike before I took it apart.  I'm guessing it's the starter switch. 

Tomorrow I'll figure out what to do next.  Maybe push it down the road and try bump starting.