Topic: What's wrong with my bike? (Video)

[BigBoi]

No.  I had you disconnect the battery to take it out of the electrical picture.  Frankly, I don't trust your battery.

While you have the alternator disconnected, measure the resistance of the field coil. (White and Green wires going into it.)  I believe the 750's are in the neighbor hood of 6.8 ohms. (Did you do this already?  I may have missed the post.)
Then measure between the alternator yellows.  It should be very near zero, like 0.2 ohm-ish, not including meter lead resistance.
Then measure between the yellow and engine case.  (should be infinity)

Alright, lots to report here. First, I replaced the battery with a new one. The last one was tested and they found it to be defective. (Yes it's true)

So I ran the tests above and both my stator and field coil seem to be ok (0.08 ohms on the stator wires, 7.2 ohms on the field coil). I put the bike all back together (with a new starter I picked up...it works!), and ran some more tests.

First things first, there's certainly still a problem. I can see now why the last battery was toast, I'm overcharging bigtime. I'm getting like 17V at idle! Have a look at this video I made today. Also, when I turn my key switch to the off position when the bike is running, it doesn't shut off the bike (see video).

I think I have the issue narrowed down to either the key switch or the regulator. Can someone point me in the right direction to test them?

[scottly]

Nice video. Very helpful. The motor continuing to run after the ign is turned off is odd. Double check your regulator connections. Make sure the wires are on the right terminals.

[TwoTired]

Check the V on the Black to the Vreg and also on the White.  With the battery at 15 V and above there should be zero volts on the white wire.  If not, the regulator is either bypassed or no good.

If the key won't turn the bike off, then you know why you battery drains.  The bar control stop switch only shuts off power to the ign. coils.

You will have to investigate a miss-wire or a bad key switch.

Not good to maintain 17+ volts on a fully charged battery, btw.

[scottly]

It's also odd that the V gets to 17V so fast, and at such low speeds. Where do you have the negative lead of your meter attached? Measure the battery voltage directly at the battery with both meter leads. 

[BigBoi]

It's also odd that the V gets to 17V so fast, and at such low speeds. Where do you have the negative lead of your meter attached? Measure the battery voltage directly at the battery with both meter leads. 

Have a look at the video again...I had them directly on the battery negative and positive.

[BigBoi]

Check the V on the Black to the Vreg and also on the White.  With the battery at 15 V and above there should be zero volts on the white wire.  If not, the regulator is either bypassed or no good.

If the key won't turn the bike off, then you know why you battery drains.  The bar control stop switch only shuts off power to the ign. coils.

You will have to investigate a miss-wire or a bad key switch.

Not good to maintain 17+ volts on a fully charged battery, btw.

Can you clarify this for me? How do I check the voltage on the black and white to the regulator? I want to make sure I'm doing this exactly correctly? Does the bike have to be running?

[scottly]

I see the red meter lead attached to the battery, but I don't see the black meter lead at all.
BTW, the running after shutting the switch off IS a new problem, right?

[BigBoi]

I see the red meter lead attached to the battery, but I don't see the black meter lead at all.
BTW, the running after shutting the switch off IS a new problem, right?

Yes it is. My habit with bikes is always using the kill switch to turn it off...never tried the key on this bike. The issue could have been there all along though.

[scottly]

Measure directly across the battery terminals. Also, I'm curious what the meter reads when you turn off the key and the motor is still running.

[Duke McDukiedook]

It was suggested here a few years ago that the honda clearances should be opened up .001.  If memory serves me right, that would be .003 intake, .004 exhaust.

I think those settings are only for a 750.

[TwoTired]

while engine is running...

Black probe on green, red probe on Vreg Black - Note reading

Black probe on green, red probe on Vreg White - Note reading

Black probe on Vreg Black, Red probe on Battery POS terminal - Note reading

Black probe on Vreg green, red probe on Battery NEG - Note reading

Do these tests quickly.  Plan what you are going to do before hand, so as not to waste time while the engine is running.  The overcharge is eventual death to the battery.  If you notice the battery getting warm/hot, stop the charging immediately.
You can reduce the battery overcharge rate by turning on all lighting.
You should be able to stop all charging by disconnecting the White wire for the alternator.

[scottly]

Also, same measurements as above, engine not running, key off, kill switch in "run" position.

[BigBoi]

Measure directly across the battery terminals. Also, I'm curious what the meter reads when you turn off the key and the motor is still running.

I was measuring directly across the terminals. (See video, the black lead is directly on the battery's negative)

I'll measure that for you tomorrow.

[scottly]

OK, now I see it, after watching the video for the umpteenth time. Damn, it's hell getting old!

[8 Track]

It was suggested here a few years ago that the honda clearances should be opened up .001.  If memory serves me right, that would be .003 intake, .004 exhaust.

I think those settings are only for a 750.

Possibly.  It was mentioned in a 750 thread and I don't recall any other cc's being mentioned.  I will edit my original post.

[BigBoi]

AND THE VERDICT IS:

Bad voltage regulator.

Swapped it out with another unit this morning, charging, key ignition...it all works perfectly.

I watched the voltage through the RPM range and it was correct according to the manual.

Guys. A huge thank you for getting me through this. No really. Huge. I'd still be crying in my garage right now.

[8 Track]

AND THE VERDICT IS:

Bad voltage regulator.




... I'd still be crying in my garage right now.

That's great!


As far as the second part goes- upset in the garage?  Nahhh, come on, really?

[TwoTired]

The Vreg fixed the key off problem, too?

I suppose if the vreg shorted internally the red to the black, that would do it.   I'm not used to the combined reg/rect units.  The separate units would not have this problem.
It also explains why you had battery draining issues, as you could never turn the bike off, and stopping current from flowing from the battery.

Good job with perseverance there, BigBoi!

[scottly]

That's great, BigBoi! Be aware that the drain through the points probably didn't do them any good. Does the bike run any better now that the ignition system is getting full voltage?

TT, I could not figure out how the bike could stay running. Thanks for reminding me it was a combined unit; I never would have put 2 and 2 togther!    

[BigBoi]

That's great, BigBoi! Be aware that the drain through the points probably didn't do them any good. Does the bike run any better now that the ignition system is getting full voltage?

TT, I could not figure out how the bike could stay running. Thanks for reminding me it was a combined unit; I never would have put 2 and 2 togther!    

Bike runs great. Took it for it's first spin today! So stoked over here guys.

My first run on a CB750 by the way...I like it way more than I thought I would! (Was a cruiser guy before)

[scottly]

I'd like to ask a favor of you, BigBoi. Would you be willing to help me make an instructional video of what to expect from a properly operating charging system? A picture is worth a thousand words, a video is worth giga-words...
Scott

[Frostyboy]

In the battery issue, I've got some info. When the motor was running, I measured the battery voltage and it was at 14->14.5. This was at 1100 RPM (idle for now).

I also checked the voltage on the battery when the bike was off, and it was at 11.57V. I unplugged the rectifier and the regulator. A half hour later, the voltage had dropped to 11.23V. So something else is drawing power.

The charging figures back here seemed quite normal. The battery was subsequently condemned. The charging figure suddenly moves up to 17v after much disconnecting, reconnecting, probing & measuring. I'm just a bit suspicious that something untoward didn't occur during all this poking about.

All that aside, I'm pleased that it's finally a goer. Enjoy the ride mate, I hope to be back on the road soon myself.

[scottly]

You raise some very valid points, Frostyboy. Sometimes it's easy to get lost in the heat of the battle...

[Frostyboy]

Sometimes it's easy to get lost in the heat of the battle...

So true, however this thread will now be a good reference for charging system analysis after all the excellent info posted by yourself & TT.

Didn't this all start because there was a question about "white smoke"?
It seemed to progress to quite a few different issues along the way.
Cheers.

[BigBoi]

So true. I'm pretty sure the "white smoke" was just condensation though. After a ride, it seems to have subsided.