Topic: Help, Broke Down Waukegan IL - Starter Problems

[YoungBlood]

I was on a road trip to UP. I stop, get gas, turn the key on (kill switch is off), but the bike starts cranking. Bike starts but the alternator makes this screaming noise. I kill the bike, try again. Same problem. Kill switch off, key on, it’s trying to crank, screaming noise from alternator.

Battery then drained fast, I tried kicking and kicking. No start. I asked for someone to jump the bike... no start. I’m waiting for autozone to charge the battery to full charge, then I’m going straight back to Chicago (no stops) to figure out the problem.

I tried jumping the solenoid, but no go. Any ideas? Why is the bike trying to start when the starter switch is off but key on? And what’s with the alternator noise. This is a new problem, bike was running like a champ before the gas stop.

[BenelliSEI]

If your starter turns over as soon as you turn key “ON” either the button switch is stuck “ON” (or shorting in the housing), or the solenoid itself is stuck closed. Something is making the power stay on to that starter?

I wonder how long that’s been happening and maybe the noise is not the alternator but the starter clutch? I hope I’m wrong. Start with figuring out what’s engaging the starter.....

[scottly]

If it was a stuck solenoid, the starter would crank even with the key off, so the problem must be with the starter button. Disconnect one of the small solenoid wires; this should disable the starter so you can run the bike by kick-starting it. 

[YoungBlood]

How do I disconnect one of the starter switch wires on the solenoid?? I’m an electrical dummy, is there a connector somewhere running off that sauntering post?

[scottly]

Trace that yellow wire; it will have a bullet connector on the end that you can unplug.

[YoungBlood]

Thank you! I’m still waiting for the battery to finish charging, then heading back to the gas station. With that wire disconnected the bike should not try to start with the key on, kill switch off, because I have killed power from the entire starter switch assembly (whether on or off).

Also now thinking, I remember when I turned the starter switch to on, key on, bike didn’t start. So this is all making some sense to me.

[scottly]

The yellow wire goes into a black sleeve with the other solenoid wire.
Kill switch only shuts off power to the ignition coils, it has nothing to do with the starter. Does your bike have a headlight that's always on, except for when the starter button is pressed? If so, the headlight may not work with a buggered start button.

[YoungBlood]

The headlight is always on when the key switch is “on”. I’ve never noticed the light turning off when hitting the starter button.

[Bodi]

"I’ve never noticed the light turning off when hitting the starter button."

This works by running the headlight power through the SPDT starter button: when you press it it cuts power to the headlight and powers the solenoid.
Running headlight power through this tiny switch tends to damage it. Replacement switches from Emgo etc are weaker than OEM, OEM is NLA.
So to avoid start button switch burnouts, a relay can be installed to maintain the headlight cutout - or the switch can just be bypassed connecting the black/red headlight fuse power wire directly to a black wire. In my experience it does not make any difference to starting or battery charging to have the headlight on when using the starter.

[YoungBlood]

Thanks everyone. I got the bike home last night, no lights, but I hard wired the front light from the battery. I also swapped two of the rear running wires (male with another female, and vice-versa). Thus I was able to get the rear running light to stay on.

Bodi, when you say a "black wire", do you mean running my own wire aside from the stock wiring? Or is there a spare black wire just lying around somewhere in the headlight assembly?

How do I fix up my starter button? The factory manual does not have any info for my 75' CB750F. And this older post has no pictures anymore: http://forums.sohc4.net/index.php/topic,80532.0.html  . Pictures would really help! I have a volt meter now, I just need directions as to finding the "short", I assume there is one?

Lastly, I do not mind completely saying screw the starter button for the time being. I'm young, and I like my kick start  . I just need my lights to be running normally, with running lights, and brake light!

[bryanj]

The only "fix" for the starter switch is a new oe as the internals are not availale seperately, there was a post years back where somebody 3d pronted the plastic bit that breaks but havet heard anything recently

[BenelliSEI]

Do you have an on/off switch for the light on the RHS bar switch? If you put all the wiring back the way you started off, do they go on/off? If not, start with the fuse? Does turning on the ignition key send power to the switch? Pushing the starter does turn light circuit off, so that starter button could be the entire problem.... if you are not comfortable testing all the functions wit a meter, the best solution is to buy a complete RHS switch. All the wires are colour coded, so swapping in a new one MAY solve all your problems.....

[YoungBlood]

I'm going to take a look at the starter switch, and send some pictures shortly. Could it be that a wire is shorting internally as Benelli said?
Is there a way around the starter switch, ultimately leaving it deactivated (kick only), but I can regain my lighting system? With the yellow/green bullet connector disconnected from the solenoid and starter button switch, can I somehow bypass the starter unit but keep the lights?
Benelli: I do not have on/off for lights. Only Low/High dampening, which is on the clutch handlebar. The throttle body has off/run/off and start button. My concern in testing power to the starter button is I will have to reconnect that solenoid yellow/green bullet, thus re-energizing the starter and draining the battery. But I will ultimately have to do this, no? To test the start button switch.

[Jerry Rxman Griffin aka MuthaF'er]

Inside your handlebar/starter switch you will find a little plastic box that the starter button goes into. My bet is it broke. As was mentioned someone was 3D printing a replacement box. And some have rigged a new button. Other than that as mentioned is to get a replacement handlebar control.     

[YoungBlood]

That's a pretty expensive part, right? ~ $100? Is that box where the button, wires, contacts, etc irreparable? Or inaccessible?

Again, I don't mind losing the start button for the time being. I just want the lights to operate, but I understand it is tied into the wiring circuit with the button. Is there a sure-tell guide to reroute the wiring and bypass this button?

Or better yet, is there a way to open up that box, clean everything up, look for shorts with volt meter, and repair it without buying a replacement?

[Alan F.]

Or better yet, is there a way to open up that box, clean everything up, look for shorts with volt meter, and repair it without buying a replacement?

That may or may not be possible depending what you find when you take it apart to look.

There are less expensive 'pattern parts' replicas, made with switches rated for less correct than the originals. Some are better than others, but I don't know which.

Depending on your specific bike, you can bypass the start button and keep your lights, but you want to be sure you're working from the correct wiring diagram, since there were changes year to year.

What's your bike again? Photo of headstock tag would be very specific. Black out the last four digits of your vin# for security reasons if you post this pic.

[YoungBlood]

Thanks Alan, will do, one moment.

[YoungBlood]

Vin, about to open up starter off on console, will send pic soon

[YoungBlood]

From left to right into starter button housing. Black wire, yellow/red, black/red

Also will send pic of wiring diagram from my Haynes manual for 750F

[YoungBlood]

I believe this is for 75 model, not sure

[YoungBlood]

The little box was cracked, some pieces fell apart

[YoungBlood]

Pieces

[bryanj]

Refer back to my previous answer, that "box" is nt availableseperately, if you connect the black to the black red your lights will beon as soon as you turn on the ey BUT that will drain the battery and MAY make for weak sparad bad starting

[BenelliSEI]

FYI..... a new switch is $50.00 at <vintagecb750.com>

[Alan F.]

First bag all of those pieces in a zip-lock bag with a note including the date and save them.

I'm not sure about your diagram, I'll always trust a Honda manual above all others. Sometimes other brand manuals have different presentation which can aid in better understanding something though. I downloaded this from the Manuals Library here on the forums. It's a .pdf, I screenshot and hosted it so we can see it large in your thread here.