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Discussion Starter #1
Hi everyone,

Very new to this forum and not exactly mechanically inclined but I’m patient, thorough and willing. I have a 78 Hondamatic that I aspire to convert in to a cafe racer in phases. The bike has not run since mid 2000’s so I’m trying to methodically bring it back to life. So far I’ve done the following:
Oil & filter change
New battery
New spark plugs
New starter relay/ magnetic switch
New ignition switch
Verified starter motor working
Verified fuses are intact
Tested all lights/ turn signals work
So right now I’m stuck because I can’t get the electrical starter to engage when I push the start button. I’m using both an Ancil PB100 circuit tester and a multimeter to make sure current is reaching the start button or other components. I can also bridge the connection (close the circuit) on the starter relay and the starter motor spins, so I think the wiring is good and correct.
Tracing the wires from the starter relay, I see the yellow red wire goes all the way to the starter button. When I check the voltage, I get confirmation that current is present with the ignition on and the reading is about 5.6 volts. I’m assuming because of the coil in the relay. There’s a
 

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Odd, that's how I actually found it. If you go to the 3 dot menu at the upper right of the post you can edit it and add what you wanted to finish it with
 

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Now to check the grounding circuits for the solenoid. The clutch lever safety switch and the neutral switch as well as the starter diode. If the diode is missing the grounding circuit will not work and the solenoid will be dead.
On the left side electrical panel look for a small black box with a 2 wire connector, it's usually loose behind the mounting panel.
 

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Is the neutral light on. With the bike on the center stand turn on the key switch and you should see the oil light and the neutral lights on. Dont start the motor but put the motor in gear. Did the neutral light go out and the 1 st gear light come on. Shift back to neutral and the neutral light should come back on. you should have 12 volts to the starter switch at the gray wire. The A model has a shift change relay that wont allow the motor to start in gear. In neutral the transistor is on and grounds the starter switch , in gear the transistor is off and the starter switch is not grounded. If the motor is in neutral and neutral light is on then you should have 12 volts to the grey wire and the problem is in the switch . If you dont have 12 volts to the grey wire then the problem is in the change switch relay.or the wring . Dumb question is the battery fully charge.it could show 12 volts but test it under load..

Let us know .

Bill
 

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Discussion Starter #8
Thanks for the feedback Bill. Here is what I have. Also, I’m assuming that by “starter switch” you mean the start button you press on the handle bars to start the bike.

Does neutral light come on with the ignition on? Yes
  • Do the oil and neutral lights come on with the ignition on? Yes
  • Does the neutral light turn off when the bike is in 1st gear? No
  • Does the 1 light come on in 1st gear? Yes
There is no grey wire to the starter switch. In my case, it may be a black wire.

I have a yellow w/red, black and black w/red. As you can see in the pic:
Yellow/red- 4.5 volts
Black - 12.3 volts
Black/red - ground (off and on)


It sounds as if based on what I’m hearing, I could have a bad starter. Not sure that’s an Amazon part. Thoughts?
 

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The grey wire runs from the change switch relay and supplies power to the starter magmetic switch. The R/Y wire goes from the magmetic switch to the starter button. If working the R/Y goes to ground and completes the circuit so the starter will work. B/R is not the ground but runs to the fuse panel and goes to the lights.Black is a power supply to the bike.Green is ground.
Dont do anything till you find whats going on with the change switch . The neutral switch and the 1st gear lights should not be on at the same.time.The change switch controls the change switch relay. The relay controls the starter switch.Remove the left side cover and the remove the change switch carefully removing the wiring under the left side cover.Dont loose the alum washer under the switch it sets the clearance between the change switch and the shift drum. see if the plunger moves in and out of the change switch then test the two wires and see if the plunger is out you should have power and when you push the plunger into the switch you should not have power. let me know what you find..

Bill
 

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Just to clarify what is what at the start switch:
Black is incoming battery positive (power switched on by key)......
When you depress the button, this power is sent via yellow/red wire to the solenoid.......
When the button is released, the power goes to and through the black/red wire to the headlight fuse and continues beyond the fuse as the yellow/black wire to the headlight high/low switch.....Depending on that switches position, it emerges as either white (low beam) or blue (high beam) to the headlight..... The headlight's green grounding wire provides the return to the battery.....
 

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Feel free to phone me about this, I believe your problem is at the starter switch......540-525-5199
 

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Ok so I am looking at it backwards the power comes thru the Y/R wire to the solenoid , then thru the grey wire and grounds thru the transistor .
Thanks 66 sprint.

Bill
 

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Discussion Starter #15
Just to clarify what is what at the start switch:
Black is incoming battery positive (power switched on by key)......
When you depress the button, this power is sent via yellow/red wire to the solenoid.......
When the button is released, the power goes to and through the black/red wire to the headlight fuse and continues beyond the fuse as the yellow/black wire to the headlight high/low switch.....Depending on that switches position, it emerges as either white (low beam) or blue (high beam) to the headlight..... The headlight's green grounding wire provides the return to the battery.....
So I got to thinking about this since I have the headlight pulled off/ disconnected right now. So I put it back on and nothing. Then using the electric probe, I tested the head light and it doesn’t work anymore. I haven’t dropped it or bumped it and it was working before but not anymore. Following your logic, I don’t think this matters since the power is carried back to the solenoid by the yellow red wire, but I wanted to verify with you guys. Having a non functioning or disconnected headlight should not keep current from reaching the starter motor, right? Is my main culprit the starter button still?
 

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Phone while at bike with a multimeter.....Now is good for me......
 

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Discussion Starter #18
Except he's not on now... he must be busy like I am, but I doubt for the same reason :p
So sixty six sprint was generous enough to spend an hour and a half on the phone with me helping to trouble shoot issues. So now, we’ve gotten to the point where we believe either the changing relay or the change switch is “leaking” voltage to the green/red wire that runs from the starter solenoid (starter relay switch) to the wiring harness. Once I connect the yellow/ red wire to the same solenoid (starter relay switch) the yellow/ red wire also registers 4.3 volts all the way to the electric starter button on the handle bars (with the ignition on). I guess my question now is to ask the experts on the site if the changing relay and the change switch can be “tested” to see if they are good. If not, then should I try to shop for replacements? I started to search on the internet and so far they don’t seem to be easy components to find. Any thoughts and guidance is greatly appreciated. Again, a huge thanks to sixty six sprint for patiently working with me over the phone Saturday!
 

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Steve - 66sprint - IS as good an expert as there is here, so if he believes the switches either need cleanup/repair/replacement, I'd go with his suggestion
 

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I'll defer to longdistancerider and other members who are vastly more familiar with these bikes (particularly the A model) than I........
I'm fairly decent with electrical, but not so much with electronics........ Having no real idea of the exact functioning of those two components, the best I could do was track the problems to the apparent sources.......I'm far more comfortable with the pre-1979 bikes.......



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