77 Honda cb550 electrical question...

Hi everyone,

I'm hoping someone on this forum may be able to help me out. About a month ago I tried to start my bike and the battery seemed dead (nothing turned on). New battery installed last year. I was in a rush so I put the battery on a trickle charger and when I got home from work the bike started no problem and for the last month I haven't had any issues. This morning when I went to start the bike the same thing happened but this time all the lights turned on but by the time I tried to start the bike it died. So once again I put it on the trickle charger and when I got home it started and I checked the voltage and it came back around 12.35. So tonight I decided to take the bike out for a quick ride to make sure everything was ok. Bike started no problem and about 10 minutes out the bike all of a sudden turned off (while riding) and tuned back on about 2-3 seconds later. I decided to turn around and head back home and about 2 minutes later the bike turned off (while riding still) and would't turn back on. I pulled over and waited a few minutes and tried to start the bike again and the bike decided to turn on and start so I finally got home and decided to ride up and down a laneway behind my house to see if I could replicate the issue and once again it turned off one more time and a second later turned back on. When it turned off for the 1 second the bike jerked forward almost like everything died with it until it turned back on. I checked the voltage again and it was around the same as before (12.35).

Hopefully this description is detailed enough. I'm not technical at all but if someone has an idea of what this issue could be that would be very helpful. Even better would be if someone thinks they can fix the issue and is familiar with these old style bikes and could come to my place and potential solve the problem. I would obviously pay you for your time. I'm located at queen and dufferin area.

Thanks guys!

Hey Kyle , I just solved an electrical issue on my bike. They are a bit of pain,,

First thing I would do is fully charge up your batter then take it to an auto parts store and ask them to do a load test, (it's free)

Then come back home and use a multimeter to check your recharging system.

After that I would disconnect all cables to batter clean them up and and reconnect and also do this with your ground to chassis.

Does your bike use breakers or fuses? If breakers them your main breaker maybe acting up,

After that I would search for a loose ground cable, kickstand or ignition switch ,

Start with the basics
I started out with the complicated stuff and wasted a ton of time and it turned out to be basics .

Find the electrical schematic for your bike. Do you know how to use a multimeter? If not, then you'll need to learn. Old bikes can have corrosion of electrical connections, and may need cleaning or replacement. You'll need to check all the wiring and all connectors on your bike using a multimeter, as a visual check is not sufficient. Something is interrupting the power from the battery to your engine. Anything along that route needs to be checked, which includes your ignition switch, master fuse, etc.

While this electrical check may take a bunch of hours, it will pay off in increased reliability. Without a full electrical check your bike is unreliable and might strand you somewhere remote.

Start the bike with the volt meter on. Starting with the battery cables, shake the wires and watch the meter until you find the problem. You obviously have a bad connection somewhere. The electrical system on an old CB isn't that complicated. When you run the bike the wire likely shakes and cuts out.

Those bikes had a nasty habit of rattling the guts out of their ignition switches.
Unbolt the switch from the top crown, you'll see that on the bottom where the wire harness plugs in its made of plastic.
If there's any slop where the plastic meets the main metal tumbler it will shut off.

Thanks guys for all the feedback. As I mentioned originally I love riding my bike but when it comes to fixing these type of issues I'm pretty useless. This morning I will hook the bike up to a multimeter and see what the battery reads. From all the suggestions I think my best bet is keeping that connected and playing around with different wires to see if I can find where the issue may be but still if I do find the issue trying to fix it is a whole other situation.

Does anyone know a mechanic located downtown (I'm at dufferin and queen). Even better would be someone coming to my place.

Thanks

are you running the stock fuse box, or have the fuses been upgraded to blade-style? Some times when that conversion is made you will find that wires shake and short out. That is what happened to mine too (i have a 78 CB550 - my build thread is on here in the project tutorials section). Also, TK4 is right. all the power for the bike (all 15A or whatever) is routed through the key switch in these bikes, so if the connector or innards of the switch are not perfect you will get A) an intermittent short, or B) a very hot and melty key switch.

Battery voltage is not a big deal on these bikes, you will probably notice a significant dimming of headlight/tail lights instead of an abrupt loss of all electrics if the battery is low. The charging system however on these bikes are fairly poor, but the bike can make enough to sustain itself when running, so will most likely experience a slow death instead of an abrupt one. I would look at body grounds and their connection to the battery (in addition to the key switch) as places that could cause the described shenanigans.