Topic: Ignition or battery issues?

[dagger_72]

Hello all!

First troubleshooting post on the forum! I am a total beginner, who inherited a working bike and swiftly started learning lessons the hard way. I haven't been able to start it and I think I blew my battery but I'm not sure if it's something else with the ignition or electronics. Short story version: My battery reads 13V off maintainer, lights come on when battery is installed, but all lights go off when electric start button pressed. During button press and after shutoff battery reads 12.6V. Read 12.3V across solenoid terminals with battery plugged in and key + ignition switch on. Shorting solenoid terminals with a screwdriver makes no noise (didn't unplug anything).

For the full story of what's going on I also included details about my carb flooding troubles, since I'm not sure if plugs were affected by flooding, please excuse that these bits of info are in the wrong board. Im not sure what info is important.

Long story version:

I acquired a '72 cb500 that was used for commuting and was able to start from cold no issue. I left it parked in the garage while I got paperwork sorted for about two weeks. Once I got the plates I went to check the controls, all bike electronics worked, only weird things that stood out to me (or maybe im just learning) were that the blinkers needed the headlight on on in order to function at first, and the tail light would stay on when the key was out of the ignition. I had to toggle the key back and forth a few times as well as the light switch to get the tail light to turn off when the key was out. Blinkers eventually worked on their own without the headlight but the light needed to be switched on and off first before they worked on their own. I went to start it up. electric starter sounded like it was working, I heard some whining, and then heard gas spraying on the floor. PO had this same issue with carb 3 flooding. Turned everything off, cleaned up the floor and let it all air out.

About two days later I went down and attempted to start it again, heard the high pitched whine when pressing the starter button, then I cant remember what happened next in detail but I think the sound stopped and the button press was either silent or really dim whirring. This is where I really messed up. With the fuel on, choke half open, key and ignition switch off, I pumped the kick starter three times and then turned the key and ignition switch on and tried kick starting the bike a few times. Quickly learned that was a mistake when gas started pouring out of carbs 3 and 4, this time I think gas even came out of the bowl seam because the seam looked like liquid was dripping down the sides of the bowl. Wasn't able to start it. The whole thing took forever to clean up. Not sure if I flooded the engine. Engine oil on the dip stick looked and smelled ok, sniffed by spark plugs with the cap off and it didn't look wet or smelled like gas.

Since the starter wasn't sounding like it did when I first tried the bike, I took the battery out and charged it until full. Then the mistakes continued. When reinstalling the battery I shorted it with a metal tool with the terminals mostly connected. Big sparks shower and a few bite marks on my tool. Checked the main fuse, its intact and meter reads continuity. No battery swelling even after several days. I took out and charged the same battery up again. This time I install it without fireworks and the bike indicator lights turn on. But once I hit the starter button everything turns off. I check the battery and it still reads 12.6V. If I turn the key again the lights do not come back on. I have repeated this battery recharge and button press process three times and the result is always the same. Solenoid makes no noise when shorting with a screwdriver, and the battery reads 12.6 under load and after power goes off.

Is it a problem with the battery since the indicator lights come back on after topping up? Or is it something with the solenoid? 

Thank you!

[HondaMan]

The last item sounds like a bad battery ground connection into the wiring harness. The main ground wire for the engine runs straight down from the battery (-) terminal on the right as you look at the battery, to the frame-engine connection plate at the top right rear of the engine (if you have the correct battery: there are some out there that are the same size with the terminals reversed! I had one of those...)

There is also a green grounding wire for the bike's wiring harness, which is tied to the frame up under the left side of the gas tank, using the top left coil mounting bolt to hold it to the frame. The frame must be clean there, too. If this connection is dirty, or if the main cable to the frame is loose, the bike will act like you are describing.

About the taillight: on the ignition key there are 3 positions: OFF-RUN-PARK. In the PARK position the taillight stays on when you pull out the key. That is useful in Europe in some places, but in the USA not so much.

[HondaMan]

The carb problems will have to be solved by taking them out, cleaning their fuel lines and float bowls and float valves in those bowls. You will need to check the fuel tank for rust: that is what often causes this problem with the carbs: it jams the fuel valves in the carbs and makes their bowls overflow.

[scottly]

My battery reads 13V off maintainer, lights come on when battery is installed, but all lights go off when electric start button pressed. During button press and after shutoff battery reads 12.6V.


the tail light would stay on when the key was out of the ignition.

If the key was turned to the "park" position, the tail light will be on and the key can be removed, but nothing else works. If the tail light stayed on with the key in the off position, it would indicate a bad ignition switch. If the battery still reads 12.6 volts with the starter button pressed, and all lights go out, it may again indicate a bad ignition switch. The switch can be bypassed for testing purposes by connecting a jumper between the red wire and the black wire; just remember to disconnect the jumper when done. There may also be a poor connection between the battery negative terminal to frame ground, or the battery positive terminal to the solenoid post and harness red wire.

[Deltarider]

Dagger, to begin with: read the Owner's Manual! It is here: https://www.honda4fun.com/dwnload/Owners-Manual/CB500-K1-Owners-Manual.pdf
The wiring diagram is here: http://manuals.sohc4.net/cb500/technical_reference/WD500BW.pdf
Now to your carbs. No need to pull the carbs yet. Practically all maintenance can be done with carbs in situ. First diagnose the problem.
If there's leaking caused by overflow, identify which carb(s) is/are peeing.
Therefore you disconnect all 4 overflow tubes. Do this gently! You don't want to damage anything. Open petcock and see if and which brass pipes(s) pee.
Carb peeing fuel out its overflow pipe, indicates its float needle doesn't close the valve. It can be caused by even a very small particle of dirt between the float needle's tip and the valve or the float itself is hindered in its movement.
1. Tap with the stub end of a screwdiver floatbowl of the suspect carb(s) and hope this will help to get rid of the dirt.
2. If not, close petcock, unscrew the drain plug completely. Now with the drain plug removed, open and close the petcock a few times, to create a flush of fuel that can flush out the dirt between the float needle's tip (that is now down) and the valve.
3. When needed, combine step 2 and 3.
In most cases this does it. Ofcourse you will collect all the fuel - inspect it for dirt or excessive rust - and pour it in your tank again.
In case there's no flow into the carbbowl, it can indicate to a sticking valve needle. Tapping the carb bowl as described above can help. When the problem reappears, you may want to add a socalled fuel system cleaner additive to the fuel in your tank. It can do wonders.
Then this. CB500s are very sensitive to a correct fuel supply. Standard length of the fuellines is 18 and 30 cm length for models that have the bowltype fuelcock. Later models have a different petcock. They need a length of 17 and 28cm resp. Use the clamp for the routing of the fuelline to the 3 and 4 carb (see pic). Ideal ID is 5,5mm. Abstain from extra inline fuelfilters! They often lead to irregularities.
If all steps above have failed, you will have to remove the floatbowls for further inspection. I can do it with carbs in situ. Some prefer to pull the rack.

[newday777]

I hope you have good liability and comprehensive  insurance covering the bike and renters insurance too if this is all happening in your "parking garage"......
The mix of leaking gas and sparks is not a good combination 😕 .
A good, new, ABC Fire extinguisher right by your bike is highly recommended.
Definitely, as Mark said above, you will need to address immediately the leaking carbs and rusted tank(IIRC you mentioned rust in the bottom in another thread??). Even light surface rust will flake off and clog the float valves.

If you haven't heard yet, HondaMan has a newly released CB500/550 restoration book out that will be an invaluable tool for you to help guide you through your journey.
It's temporarily on hold to fix a typo found so keep watching this link, should be back up tomorrow???

https://www.lulu.com/search

Your description of volts on your battery sounds like it is okay if you load tested it properly. Load tests should show if there is an internal short making the battery bad.
Autozone will load test the battery for free if you take the battery to them.

[rotortiller]

Always hook up the battery ground last, that way if you short the positive to the frame ground with a tool nothing happens. If you manage to somehow short the battery terminals directly then it is probably time to leave the maintenance to someone else lol!

[dagger_72]

Always hook up the battery ground last, that way if you short the positive to the frame ground with a tool nothing happens. If you manage to somehow short the battery terminals directly then it is probably time to leave the maintenance to someone else lol!

I did manage to short them directly. A lesson on tool selection learned 

This bike has had better owners, but I am down to learn the right way to do things 

[dagger_72]

I hope you have good liability and comprehensive  insurance covering the bike and renters insurance too if this is all happening in your "parking garage"......
The mix of leaking gas and sparks is not a good combination 😕 .
A good, new, ABC Fire extinguisher right by your bike is highly recommended.
Definitely, as Mark said above, you will need to address immediately the leaking carbs and rusted tank(IIRC you mentioned rust in the bottom in another thread??). Even light surface rust will flake off and clog the float valves.

If you haven't heard yet, HondaMan has a newly released CB500/550 restoration book out that will be an invaluable tool for you to help guide you through your journey.
It's temporarily on hold to fix a typo found so keep watching this link, should be back up tomorrow???

https://www.lulu.com/search

Your description of volts on your battery sounds like it is okay if you load tested it properly. Load tests should show if there is an internal short making the battery bad.
Autozone will load test the battery for free if you take the battery to them.

Ahhh, I was wondering why the link didn't work. Tried looking into the book earlier this week.

As far as bike and apt insurance and fire extinguishers go, check, check, and check. Good call. I always keep a small extinguisher in my car, and have it out and next to the bike when I'm troubleshooting. Don't want to be the reason the whole building has to evacuate.

The rust I mentioned in a previous post was on the outside, but the inside does have some surface rust. This is very helpful. Sounds like I should do some due diligence on the tank.

[dagger_72]

Dagger, to begin with: read the Owner's Manual! It is here: https://www.honda4fun.com/dwnload/Owners-Manual/CB500-K1-Owners-Manual.pdf
The wiring diagram is here: http://manuals.sohc4.net/cb500/technical_reference/WD500BW.pdf
Now to your carbs. No need to pull the carbs yet. Practically all maintenance can be done with carbs in situ. First diagnose the problem.
If there's leaking caused by overflow, identify which carb(s) is/are peeing.
Therefore you disconnect all 4 overflow tubes. Do this gently! You don't want to damage anything. Open petcock and see if and which brass pipes(s) pee.
Carb peeing fuel out its overflow pipe, indicates its float needle doesn't close the valve. It can be caused by even a very small particle of dirt between the float needle's tip and the valve or the float itself is hindered in its movement.
1. Tap with the stub end of a screwdiver floatbowl of the suspect carb(s) and hope this will help to get rid of the dirt.
2. If not, close petcock, unscrew the drain plug completely. Now with the drain plug removed, open and close the petcock a few times, to create a flush of fuel that can flush out the dirt between the float needle's tip (that is now down) and the valve.
3. When needed, combine step 2 and 3.
In most cases this does it. Ofcourse you will collect all the fuel - inspect it for dirt or excessive rust - and pour it in your tank again.
In case there's no flow into the carbbowl, it can indicate to a sticking valve needle. Tapping the carb bowl as described above can help. When the problem reappears, you may want to add a socalled fuel system cleaner additive to the fuel in your tank. It can do wonders.
Then this. CB500s are very sensitive to a correct fuel supply. Standard length of the fuellines is 18 and 30 cm length for models that have the bowltype fuelcock. Later models have a different petcock. They need a length of 17 and 28cm resp. Use the clamp for the routing of the fuelline to the 3 and 4 carb (see pic). Ideal ID is 5,5mm. Abstain from extra inline fuelfilters! They often lead to irregularities.
If all steps above have failed, you will have to remove the floatbowls for further inspection. I can do it with carbs in situ. Some prefer to pull the rack.

Thank you for the advice! When you say unscrew the drain plug do you mean the large slotted soft screws at the bottom of the bowl? All four are stuck on my bike and two of them look kinda stripped. For now I sprayed them with WD40 and left overnight, will do another application and see if they budge. I don't want to bring torches into the equation. Someone elsewhere said a hair dryer would work too, I might try that to get them off. I also have some clear lines that fit the carbs I can use to monitor overflow, but I know I eventually have to get those drains open.

[dagger_72]

The carb problems will have to be solved by taking them out, cleaning their fuel lines and float bowls and float valves in those bowls. You will need to check the fuel tank for rust: that is what often causes this problem with the carbs: it jams the fuel valves in the carbs and makes their bowls overflow.

Thanks for posting about this here and in my introduction post as well! Sounds like the tank rust might be the issue since the PO replaced the float and valve for carb 3 and still had issues after. Thanks for pointing out the earlier tip to check the fuel sieve. I will definitely look at the fuel system along with electrical!

[dagger_72]

Wow thank you all for your replies! Going off Scotty and Hondaman's replies, the tail light stayed on when the key was in the 'off' position. The ground wire connection from the battery to the frame is very rusty and has a suspect section where the insulation is eaten through. Sounds like I need to maybe clean some connections and check the ignition switch.

Will circle back, but wanted to say thank you all!

[Deltarider]

To avoid doing work not needed, first diagnose.
Yes, those are the drain screws. WD-40 is good. If the slot is damaged, use pliers. Collect the fuel from each bowl and report what it looks like.
When in doubt about parts, the Parts List for your model is here: http://manuals.sohc4.net/cb500/service_manual/PL500K0_K1.pdf