Topic: first ride: 1976 CB750F. now tuning / charging issues

[riffman12]

ha thanks guys. I thought they looked pretty good. #2 is possibly a hair richer than the others, but hard to say.

As this was mostly putting around town, I think next step is to put new plugs in and do a full throttle chop and make sure my 115 mains are working well with my exhaust / K&N airbox setup

[flybox1]

so  I got some riding in today and the bike ran awesome. Smooth through the whole rpm range, pulls from all the way down low. Here's my plugs after some mixed riding. What do you guys think? I'll be doing a proper wide open plug chop later. Most of this was from 1/4 to 1/2 throttle.




closeup of #4:

Hot D@mn!!!  those are some nice looking plugs 

[Jerry Rxman Griffin aka MuthaF'er]

Without digging through the thread have you done a proper sync? Could even up the plug color just that little bit more. 

[scottly]

Big thanks to calj737 and everyone else who gave me a hand with this.


In the end, he had me wire the black from my reg/rec directly to my positive battery wire at my starter solenoid, bypassing any possible hangups in the 40 yr old harness.

This was only for testing, correct? If left connected directly to the battery, the field coil will always be energized, draining the battery when the motor isn't running.

[riffman12]

ha funny you should say that. I was about to come on here and post that my battery is dead after sitting over night 

So it sounds like that can't be a permanent solution...

[calj737]

Yep, Scottly's right. That's a mistake on my part.

Okay, Scottly, then how does he eliminate the 0.5v drop through BLACK? He's cleaned every connector from the battery through the chagrinning and key switches... With that drop, he's over-charging his battery (15.1v).

[riffman12]

ah yes my never ending electrical gremlins. I had one day of sweet riding and now back to cleaning 

Tonight I'm going to clean the main frame ground even though it looks spotless - just to rule that out. The other ground I cleaned was by the coils where they mount to the frame. Any other grounds I should be aware of and cleaning?

Then from there, given my symptoms, do you guys think the culprit connection is somewhere in my black wire circuit? Or could it be anywhere?

[calj737]

Given that you measured the voltage drop on BLACK on Saturday (where you discoed the Reg/Rec from the panel plug) that is the circuit that is problematic. All of your harness wants to be clean, but to eliminate the over-charging issue and correct my mistake on the solenoid stud, you'll need to restore that panel plug connection after isolating that drop.

[riffman12]

so I was poking around the harness and found this junction between the airbox and the oil tank. I believe it's where the electronic ignition is wired into the harness along with the the rear brake light switch:




Looks like someone used that little red 3 way clamp between the 3 black wires. Is that an ok way to connect these wires? Looks kind of hack to me...

Wondering if that could be the hang up in my system, but if so: What would be a better way to join those 3 wires?

[scottly]

Yep, Scottly's right. That's a mistake on my part.

Okay, Scottly, then how does he eliminate the 0.5v drop through BLACK? He's cleaned every connector from the battery through the chagrinning and key switches... With that drop, he's over-charging his battery (15.1v).

Like you said, a 0.5V drop is about as good as it gets for the stock harness. If the voltage drop on the ground side is not at fault (measured from the battery negative post to the green regulator wire), then one could wire a relay to switch the regulator black lead directly to battery plus, using the black harness wire to trigger the relay coil.

[Jerry Rxman Griffin aka MuthaF'er]

Looks like the power tap for my Dyna III ignition. If that thing has CUT the wire then you may have found your problem. Voltage check before and after.

[scottly]

Mike, I'll reply to your PM here, so others can learn also.
To do the positive side voltage drop test to the regulator, it's best (and easiest) to measure the drop directly, with everything connected.
Connect the meter red lead to the battery + terminal. (the terminal itself, not the wire connected to it)
Connect the black meter lead to the regulator black wire, at the junction between the harness and the reg.
With the key on, kill switch set to off, read the voltage.

To read the negative side drop, connect the black meter lead to the battery - terminal, and the red lead to the green reg wire, and read the voltage. 

[riffman12]

ok thanks guys.

Scottly, I'll give that a go.

At the moment, I can't really test my system. After my coils drained my battery the other night, I've been using my battery tender to bring it back to life. Went out last night after charging it all day, and there was acid seeping out of the cracks on top of the battery. The battery its self was quite warm.

Is that battery toast? Or is this normal?

Might just order one of those Scorpion AGM batteries

[b52bombardier1]

Save your money on buying a new AGM battery until you have the charging system sorted out. An AGM battery is even less tolerant of overcharging than a flooded lead acid battery.  The AGM will soon start to fail, bulge out the sides of the case and become difficult to remove from the battery box.

Rick

Sent from my SAMSUNG-SM-N900A using Tapatalk

[riffman12]

ok quick update. With the help of Bodi (from another thread) and Cal, I was able to wire a relay into my charging system to bypass the resistance in the 40 yr old harness.

Now I'm getting 12.5 V at 1000 rpm. 14.5 V at 5000+ rpm.

Looks to be good so far. Does anyone know if there are any negative long term issues with this setup?