Topic: 76 CB550k electrical

[MY76CB550K]

I have ridden bikes but never worked on one.  Just inherited a '76 CB550K that sat for years in an old garage.  Tag expired in '86, I am told last it was started was in around '06.  I changed the oil/filter, plugs, replaced the battery, and put fresh fuel in it (will replace the air filter once I get the bike running).  Checked to see if it'd start but I am not getting any power to anything: headlight, signals, horn, starter, etc.    Battery has tested good as has the ground.  Getting power to the fuses.  Thoughts?

[Bankerdanny]

Welcome to the group. Once you get over 4 posts you can start adding pictures, which we like in general, but also help with diagnosis in many cases.

Download the workshop manual and electrical diagrams, there are links here at the forums. Do you have a multimeter? If not you need to get one so that you can start tracing the circuits. These bikes are pretty basic from an electrical perspective, but when you are talking a 40 year old bike corrosion takes its toll.

If you have a meter you need to start with the ignition switch and confirm you have power in and out. Complete and utter lack of power anywhere would tend to indicate a bad switch. If you don't have a meter yet, I would check the ground wire from the battery to the frame. If that is bad then none of your circuits will work.

The key to dealing with electrical problems is to be systematic.

[MY76CB550K]

I appreciate it sir.  Found and downloaded the shop manuals.  Checked continuity on the ground and it was good.  Checked power on the battery and it was 12.3V.  Checked the ignition switch and it was good.  Just for fun checked continuity between the hot post and the bike and had continuity (shouldn't of course but having sat in a garage for so long figure some of the wiring could have been chewed on).  Put the voltmeter back on the battery and turned the key to ON, voltage dropped to almost nothing).  Hooked a jump box to the battery and all my lights came on.  Removed the battery and checked continuity between the hot wire and the bike and continuity was gone.  Brand new battery was bad.  Glad that problem at least ended up being simple.  I am sure cleaning and rebuilding the carbs will prove interesting.

[Bankerdanny]

The carbs are pretty easy to clean, removing them can be a pain and installing a bigger pain. Heat is your friend. use a hair dryer or heat gun to warm up the boots (be careful with if you use a heat gun not to melt the rubber).

If you can just get fresh gaskets for the carbs. The jets and needles in most carb kits can't be trusted and it is rare to need to replace the factory ones based on wear.

[BomberMann650]

I never needed a heat gun to remove carbs...

[Bankerdanny]

I've done it without too, but my experience with my '77 which also sat for 30 years was that heat made the job much easier.