Topic: 1973 Honda CB350-Four: no power

[YoungAmerican]

I bought a '73 Honda CB350-Four last year. The seller had somehow broken the electric start button on the day of shipping, but sent me a separate set of handle bars, which I dissected and got the button from. At the time (last Fall), the bike would start up.

When trying to open the right handle switch, I managed to strip on of the screws that keeps it shut. Eventually, one of my friends got it open. Inside, there was another stuck screw, which I tried to loosen with Liquid Wrench to no avail. I had to let it sit for quite some time (injury), but recently managed to get the screw out with an extractor.

After some serious finagling, I replaced the spring and button and got the electric switch put back together (way harder than it needed to be). I put the key in the ignition and turned it. For a moment, the oil pressure and neutral lights came on, so I hit the button, and they went off (I don't think this was simultaneous, I wasn't paying attention). No power.

I charged up the battery, took it to the parts store, got it checked (holds a charge), refilled the cells, and charged it the rest of the way up. Still no power (no lights, horn, oil pressure/neutral lights, etc.).

I checked the inline fuse on the battery and it was broken, so I replaced it. Still... no power at all. I'm not sure what to check next?

[elbowdeep]

Ha, I was going to say they came that way from the factory 

Might be a loose connection, bad ground.... keep looking

[YoungAmerican]

I keep looking and looking. I hate that it's getting dark at 7pm and soon it's gonna be cold. Soooo frustrated

[bollingball]

Do you have a meter? If yes then check for power on both ends of the fuse.  find where the wire goes to. I do not have a print for a 350. might go to the key sw. With the key turned on wiggle the wires at the sw. and see if gets power.

Ken

[HondaMan]

Wiggle the wires at those fuse clips, too. The clips are often corroded, might need to be replaced or cleaned with some fine sandpaper, to make contact with the fuse.

[camelman]

Use a dielectric grease on the contacts too. That'll keep corrossion at bay and reduce the likelihood of overheating your fuse. Keep the grease away from rubber parts though.

[flybox1]

turn your key to ON,
wiggle all the block connectors under your tank, in your headlight can, under the ignition switch, behind your side cover, rotate your handle bars slowly side to side....all while looking for signs of life.
you'll find it.
clean and treat every connection you touch.

[YoungAmerican]

Thanks for the tips, everyone In searching for corrosion, I am finding very, very little. The guy I bought this from kept it in surprisingly good condition, but I will look into dielectric grease, for sure

I got a multimeter today and used the few hours left of light after work to try and test all the possible connections. Keep in mind, I am not super familiar with working with electronics like this... I found two possible wonky connections. One is the tail light to connector (but the light to ignition appears fine) and the other is any point I tested on the line that runs from the battery to the ignition (which has the inline fuse casing).

The latter I want to say is most suspect. The multimeter I got has terrible instructions... but all other connections, I got some reading for resistance. These, however, I got no reading and the MM flashed -1 for a split second on each. The inline fuse itself is fine... I guess I should look into replacing that wire?

Sorry if I sound ridiculous, but, seriously, electronics... not my background Here's the wiring diagram I found, though, if anyone is curious!

[HondaMan]

Thanks for the tips, everyone In searching for corrosion, I am finding very, very little. The guy I bought this from kept it in surprisingly good condition, but I will look into dielectric grease, for sure

I got a multimeter today and used the few hours left of light after work to try and test all the possible connections. Keep in mind, I am not super familiar with working with electronics like this... I found two possible wonky connections. One is the tail light to connector (but the light to ignition appears fine) and the other is any point I tested on the line that runs from the battery to the ignition (which has the inline fuse casing).

The latter I want to say is most suspect. The multimeter I got has terrible instructions... but all other connections, I got some reading for resistance. These, however, I got no reading and the MM flashed -1 for a split second on each. The inline fuse itself is fine... I guess I should look into replacing that wire?

Sorry if I sound ridiculous, but, seriously, electronics... not my background Here's the wiring diagram I found, though, if anyone is curious!

The meter:
Just connect the Black lead to the engine or frame (bare spots) for your ground reference. Then use the Red lead to look for voltage where it should be. Set the meter to 20 volts (DC) or so maximum reading.

You might wish to turn off the Kill switch on the handlebars while you do all this, so you don't burn the points. And, maybe stick a small battery charger onto the battery terminals to avoid killing the battery altogether in this process.

I'd go at it like this:
1. First check point: the Red wire at the Start Solenoid, which goes to the battery (+) terminal. You should have battery voltage (about 12 volts) even with the key off.
2. Check the fuse clips with the fuse in place: first the side that goes back to the starter solenoid post. Then the other side. The volts should still be about 12.
3. Turn on the keyswitch, and see if any Black wire is showing 12 volts. This is the main Ignition circuit thru the whole bike.
4. Inside the headlight bucket, check the Black wires (all) for 12 volts with the key on. Then turn the Kill switch ON and check the Black/White wire: it will have about 11 volts with all the losses up to now. Also check the Black/Red (yours might be Brown/Red or Black/Yellow) that comes in from the right-side handlebar switch: this is the headlight power when the Start button is not pressed.
5. Check the Yellow/Red wire when the Start button is pressed: this is the starter solenoid.
6. Any Brown or Brown/White wire is lighting. There should be about 11 volts on them when the lights are on.

Report back what you find?

[YoungAmerican]

Thanks! Steps are soooo appreciated!

1. (red at solenoid) I got around 12 (slightly above)
2. (fuse clips) slightly above 12 on both sides with the fuse in place
3. (black ignition wires) no readings
4. (black wires in headlamp) the only ones I saw were open except what I note below, but nothing; (black/white kill) nothing; (didn't find the wire to the light you meant for black/red... is this oil pressure/neutral?)
5. (red/yellow at button) nothing...
6. (brown and brown/white) nothing

When I was in the right handle switch casing again, I was looking around at the kill switch wires and noticed one is frayed open. Whoever put this thing together last seems to have used hydraulic tools or something, because I have another insanely tight, stuck screw before I can remove the shield and examine the wiring. It looks like the black/white.

When in the headlight bucket, I noticed two wires that were black until the connection, they one was ringed light blue and the other orange. Each was connected to a solid color wire, but of the opposite color (that is a black wire ringed w light blue connected to an orange and a black ringed w orange connected to light blue). I didn't switch them b/c the blinkers (which they appear to go to according to the wiring diagram) worked last year and I didn't touch them...

I'll update this once the screw is out and I can get a look at the kill switch wiring.

[HondaMan]

Thanks! Steps are soooo appreciated!

1. (red at solenoid) I got around 12 (slightly above)
2. (fuse clips) slightly above 12 on both sides with the fuse in place
3. (black ignition wires) no readings
4. (black wires in headlamp) the only ones I saw were open except what I note below, but nothing; (black/white kill) nothing; (didn't find the wire to the light you meant for black/red... is this oil pressure/neutral?)
5. (red/yellow at button) nothing...
6. (brown and brown/white) nothing

When I was in the right handle switch casing again, I was looking around at the kill switch wires and noticed one is frayed open. Whoever put this thing together last seems to have used hydraulic tools or something, because I have another insanely tight, stuck screw before I can remove the shield and examine the wiring. It looks like the black/white.

When in the headlight bucket, I noticed two wires that were black until the connection, they one was ringed light blue and the other orange. Each was connected to a solid color wire, but of the opposite color (that is a black wire ringed w light blue connected to an orange and a black ringed w orange connected to light blue). I didn't switch them b/c the blinkers (which they appear to go to according to the wiring diagram) worked last year and I didn't touch them...

I'll update this once the screw is out and I can get a look at the kill switch wiring.

Yeah, the blinker wires in the 350F/400F are all sorts of colors....

It sounds like possibly the keyswitch is bad. There is a Red wire that goes directly to it, which is the same one as on the Starter solenoid. There should be 12 volts on that wire, right at the switch. When the switch is turned ON, it connects this Red to the Black on the same switch, which you will see when you're looking at it up close. Then, the 12 volts should appear on the Black.

If the 12 volts doesn't appear on the Black when key is ON, the switch is toasted or the wire is broken off (this happens on the back of these switches sometimes). You can also perform this check right on the connector that goes to the switch, if necessary. Sometimes the connector blades in these connectors are grungy and burnt, which will also create poor connections. You can get new ones (and a sweet crimper, cheap) from www.Vintageconnections.com (tell Del I sent you...   ).

[YoungAmerican]

Ooooo! That would be a much easier fix than I would have imagined. I started thinking all these horrible worst case scenarios  When I had tried to hassle the boot on the back of the ignition, it didn't want to move. It's very clean and nice feeling, like it might be newer and after jamming my fingers about 12 times I thought "do that last." I'll check it out tomorrow morning! Thanks! 

[YoungAmerican]

So I took the boot from the back of the ignition and found that it was taped up really well. Once I peeled the tape away, the red wire came with it. It has power at the point, but the hole it's supposed to be soldered in looks grimy and black. I shoved it in there the best I could, taped it, turned the key, and still nothing to the black wires.

So, this sounds like the ignition?

[HondaMan]

So I took the boot from the back of the ignition and found that it was taped up really well. Once I peeled the tape away, the red wire came with it. It has power at the point, but the hole it's supposed to be soldered in looks grimy and black. I shoved it in there the best I could, taped it, turned the key, and still nothing to the black wires.

So, this sounds like the ignition?

Oh, yeah.

The Red wires are sometimes melted off the back of their switches from a temporary short (or halogen headlight).

Maybe check your headlight? If it is halogen and more than 35w/35w type, the 350 won't support it, and it will melt the Red wire(s) off the keyswitch(es).

[YoungAmerican]

I ordered a new ignition switch. I'm running all over the place today, but I thought I would mention that I clipped it on and turned the key... neutral light came right on! I'm 99% sure once I put the right handle switch back together and properly mount the switch, I'm golden.

Thanks so much for all your help!!! I'm so excited (I wish I wasn't out of town this weekend so I could play)!!!