power cuts out when I turn on the headlight

kaidemarco

kaidemarco

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Joined
Oct 30, 2021
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Location
Ocean City, NJ
So now that my bike has decided to break itself in an attempt to avoid the wrath of facebook marketplace, I am going to fix it for myself.

The bike doesn't turn on, no horn, starter, or neutral light. After a little bit of shaking different areas(can't tell which but I am leaning towards under the seat or by the reg/rect), it will come back on and even start, but as soon as I turn on the headlight it will go off again.

The bike has correct positive power to the starter solenoid, and the fuse is good. But, there is no continuity to the black positive in the headlight bucket when the bike cuts out.

The ground in the headlight bucket and through the bike is good.

I can't figure out the correlation between the headlight switch and main power. Does anyone have an idea? Going to do some more investigation tomorrow.
 
Time to clean all your electrical connections and make sure they're nice and tight. My Trail 90 would cut out whenever I turned on the headlight or used the turn signals. I cleaned every connection with a small stainless brush that fit inside the female connectors and a Scotchbrite pad on the males. Did the trick and I could run all the lights with no engine problems.
 
Check your switch wiring where it runs in and out of the handlebars, sharp edges there can cut into the wires.
 
Maybe bad ground. Id clean the battery negative and frame ground and also the one from the bars to the fork bridge... tho I don't think headlight uses that one?

As a quick test, run a ground wire from the headlight ground to the battery negative and see if that fixes it
 
I have found shorts and breaks in the wiring at the headstock. Lots of resistance spots ... kill switch, key switch, in the bucket which can cause issues.
 
I had a CL350 K4 with the same headlight issue that frustrated me for a period of time. Eventually what fixed it was taking the key switch apart and cleaning the contacts inside the switch.
 
12ozPBR said:
I had a CL350 K4 with the same headlight issue that frustrated me for a period of time. Eventually what fixed it was taking the key switch apart and cleaning the contacts inside the switch.
Click to expand...
speaking of keyswitches i heard your the man to talk to about gettin a new key i have a 79 twinstar needing one
 
UPDATE: Thanks for the help, I think it is the keyswitch going bad. Last year I had to open the switch because one of the points had rusted out. I got it working consistently but it will probably come back, we shall see.
 
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