Author Topic: 1971 Honda CB500 - Charging Issue (At wits' end) (Read 14967 times)

zerodaydave · « **Reply #50 on:** July 14, 2016, 09:50:10 PM »

It's like .90v with just the key running. Sound right?

scottly · « **Reply #51 on:** July 14, 2016, 10:01:58 PM »

Should be zero, or very, very close to zero. You have a poor connection between the battery-, frame, and harness grounds. That .9 volt loss plus the 13.2 volts measured earlier would bring the charging voltage up to 14.1 volts.

zerodaydave · « **Reply #52 on:** July 14, 2016, 10:07:27 PM »

So basically just go around the bike and look at all the grounds and make sure theyre clean. Sorry I'm learning as I go. Not really sure how to troubleshoot that other than make sure they are clean.

scottly · « **Reply #53 on:** July 14, 2016, 10:21:07 PM »

No problem, as long as you are learning!

Since your wiring isn't stock, and I'm not looking at it with my own eyes, I can only give you some things to look for. Normally, there is a connection from the common green harness wire to the frame, sometimes at the coil mount under the gas tank, sometimes near the battery under the seat. You need to find this connection and make sure it's clean and properly grounded. The battery - post must also have a good connection to the frame.

zerodaydave · « **Reply #54 on:** July 14, 2016, 11:02:50 PM »

I have found it and it's connected on to the coil with the two bar end lights (which flicker at idle and when revving). I looked at the connections and it is clean. Do I need to do something special with the green wire? Can it have other accessories grounded with it?

Also it's crazy how much I've learned and how much I continue to learn from people like you and cal on this forum. Super stoked!

scottly · « **Reply #55 on:** July 14, 2016, 11:19:55 PM »

Yes, you can have other accessories grounded at the same point, but if the bar end lights are flickering, it may point to a poor/loose ground connection. Remove the bolt and make sure the connection point on the frame is clean and shiny, and all surfaces on the wiring eyelets are clean as well. When reassembling the connection, make sure the bolt clamps the eyelets firmly against the frame; a bolt that is too long will feel tight, but not clamp the eyelets properly.

zerodaydave · « **Reply #56 on:** July 14, 2016, 11:33:34 PM »

Excuse my ignorance but it can be any of the grounds right? There's nothing significant about the main green one?

zerodaydave · « **Reply #57 on:** July 15, 2016, 10:12:52 AM »

Plot twist discovered this this morning. See attached. The bike was still running because we were apparently bypassing the fuse wired directly to the battery. We removed that wire and we are now going through the fuse.

I went through all the grounds and sanded each ground down to the shiney frame.

Test results are about the same. It is just crazy how fast the battery drains when idling I barely have time to test anything before it dies. The new battery is already at 12.3v. I had to place the old one back in. At terminal 13.20. At 4-5k 13.60v. Should it be at 14.5k in those ranges? That's what the manual says.

New test results attached. Did break out of the 13.15v range I couldn't get out of yesterday.

I'm super frustrated right now. I have no idea what it could be.

zerodaydave · « **Reply #58 on:** July 15, 2016, 02:44:04 PM »

Ugh ... So I found it! And I now know what's up. Basically I was doing a compression test for another issue I was having. And when I tried to start the bike for some reason the ignition button wasn't working so I kick started the bike and drove it around the neighborhood. Came back and tested it again and this time 14.64v at 5k rpm! Turned off the bike and was super stoked! Obviously I didn't believe it so I tried to start the bike again with the starter button and it didn't work. Kick started it and only 13.50v at 5krpm what gives? Hit the ignition button again and the bike just cuts out. Turned the key off and kick started it and again 14.64v at 5k rpm. So it's something with the right hand controls! Specifically the ignition starter button. Grrr ....

Bodi · « **Reply #59 on:** July 15, 2016, 03:04:23 PM »

I can't imagine how the control switches can affect charging. I think you're on the wrong track there.
0.9V drop to the field coil isn't bad, the regulator itself has ~0.5V drop from the switching transistor.
I can't explain why the system would suddenly manage to get up to float voltage.
You've confirmed all grounds are good. What does the field coil ground to? You can attach it to a solid frame ground to be sure it's good.
You can run a jumper directly from battery "+" to the other field coil wire and see what your battery voltage is when running. This puts the alternator at 100% and - if the rectifier, wiring, and stator coil are OK - this can push the voltage over the safe limit for your battery so watch it carefully.

scottly · « **Reply #60 on:** July 15, 2016, 09:52:02 PM »

Quote from: Bodi on July 15, 2016, 03:04:23 PM

0.9V drop to the field coil isn't bad,

It is when it's between the battery minus terminal and the ground side of the field coil.

Dave, if the charging problem comes after pressing the starter button, but goes away after turning the key off and back on again, it would appear the problem is related to the M-unit. Did the electric start button ever work properly?

zerodaydave · « **Reply #61 on:** July 15, 2016, 10:12:02 PM »

Man .. .this thing. It's just so intermittent. Today I got the bike up to 14.64v at 5k rpm. Now it's back to doing the same thing. I have no idea what it is. I've looked at the grounds and they all look good. I even took sandpaper to each one straight to the frame.

The starter button did work for awhile but we have always had issues with it. And the lights are still flickering at idle and more so when i rev.

Should i be looking between the battery minus terminal and the field coil ground?

scottly · « **Reply #62 on:** July 15, 2016, 10:18:34 PM »

Does the charging system always work if you never use the start button? Are you using stock handlebar switches?

zerodaydave · « **Reply #63 on:** July 15, 2016, 10:22:04 PM »

Yeah I'm using stock handlebar switches. Both times it did work I ended up kickstarting it and not using the starter switch (which as of today no longer turns the bike on and we're not sure why yet). If you push it now all power to the bike cuts out it just dies.

scottly · « **Reply #64 on:** July 15, 2016, 10:40:13 PM »

If it were a stock wiring system, it would be much easier to trouble shoot than with an M-unit thrown into the mix. If you had a short, with a stock system you would blow a fuse, but the M-unit has built-in breakers that reset. Right now, it sounds like your issue isn't a charging fault, but an excessive load, brought on by pressing the start button. Why the load doesn't go away when the button is released, but does after the key is turned off, is a mystery....
For now, don't even try the starter button at all, and see how the charging system works.

zerodaydave · « **Reply #65 on:** July 15, 2016, 10:55:04 PM »

Cool I'll give it a try in the morning and post my results. I would love to go outside right now and rev my bike to 5k but I'm sure the neighbors would be pissed!

zerodaydave · « **Reply #66 on:** July 16, 2016, 02:35:22 PM »

Hey Cal!

Honestly we are just super frustrated right now. And yes I've talked about pushing the bike off a cliff or stuffing a rag in it and lighting it on fire lol!

My buddy has been troubleshooting it with me the entire time and I have been showing him all of the posts. I was talking about the start button. Thanks for clarification on pushing it twice to kill the engine. That's awesome and we both didn't know that. We completely bypassed the start button today by removing all the wiring from the m-unit. Still not working. We're both unclear on how to test the AUX port. Is it neutral or positive on the battery to test? Also he said he wired the start button to start on the munit not aux.

It's also difficult getting a good reading when the multimeter leads are connected to the +, - terminals because it just jumps around so much. We've tried new batteries it just does the same thing. Not when the bike is not running. Especially when we rev the engine.

Also the solenoid is bad and I bought a new one eBay. No click when you push the start button. Tested with a screwdriver and it arched but didn't activate. So we bypassed that to see if that was it and it's still the same thing.

Thank you everyone for the time and responses. I am totally new at this but I am learning a ton. I never thought I would be tearing my bike apart on the side of the road with the ability to put it back together and be on my way which I did today!

zerodaydave · « **Reply #67 on:** July 16, 2016, 06:41:45 PM »

Here you go. There is a wire running from Start right to solenoid.

Aux is 12.90 on key on and 12.80 running at idle.

I found this too. I want to say that's the issue but this bike is annoying as all hell and most likely it's not. That yellow wire was from the back of the stator connection. I believe it's a stator wire. It was hanging on by a strand and I easily plucked it off with my finger. The red wire in the pic goes to the top of the solenoid.

scottly · « **Reply #68 on:** July 16, 2016, 07:07:11 PM »

The loose yellow wire would explain the on/off charging issue!!! Those are REALLY #$%*ty crimps!!!!

zerodaydave · « **Reply #69 on:** July 16, 2016, 07:30:42 PM »

My fingers are crossed but my bike hates me. Those are some pretty #$%*ty crimps. I will let my buddy know and post an update.

Aux reading look good?

scottly · « **Reply #70 on:** July 16, 2016, 07:38:45 PM »

Solder those connections, and any others done the same way. You will have to remove the lugs from the plug housing first, and you should re-form the crimps with pliers into a more cylindrical shape. As far as any M-unit readings:

zerodaydave · « **Reply #71 on:** July 17, 2016, 10:17:06 AM »

Black is ground. And the red yellow wire is connected to a blue wire which goes to START out.

and the video is attached of the munit while bike is starting.

zerodaydave · « **Reply #72 on:** July 18, 2016, 07:47:12 AM »

Because sometimes the starter button doesn't activate the solenoid at all when you push it. You hear no click. It doesnt do anything. It was only $9 on ebay so I just grabbed a new one.

Yeah the brake is always on.

I'm going to fix the connector today and I will report back the results.

Update: fixed the connector and cleaned up the m-unit area. Pictures attached. It's still not working. Now it's not passing any voltage.

Any ideas? Beyond frustrating.

zerodaydave · « **Reply #73 on:** August 17, 2016, 11:59:08 AM »

So I actually put a jumper cable on the + terminal and connected to the white field coil wire and the bike is charging. Not at 14.5 but 13.65. Without the jumper cable it doesn't charge at all.

What's weird is with the bike running I tested the voltage all the way from the + terminal to the white field coil wire connector where it exits the stator case and there is no loss in voltage. It's the same as the battery. How weird is that.

It doesn't charge without the jumper cable.

I took a break from the bike for awhile because it was so frustrating but I'm back at it.

News:

Author Topic: 1971 Honda CB500 - Charging Issue (At wits' end) (Read 14967 times)