1974 ct70

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WENDELL OLDHAM

New Member
just bought this and put a new battery and coil in. Cleaned up flywheel and points. Cleaned carb. Runs pretty good. All brake and tail lights work. Head lights and horn not working. Think the horn switch was bad so I’m replacing it. Still can’t get the headlights to burn? Help
 
cjpayne

cjpayne

Well-Known Member
You can test the headlight with a continuity tester, but you will have to remove it first.
Are you putting the ignition switch to the 2nd position?. There may also be something wrong with the dimmer switch too.
 
W

WENDELL OLDHAM

New Member
I put the ign switch on the 2nd position. I’ve tested the new headlight. It works on both hi and low beam. Also tried it running and not running.
With the tail and brake lights working I would say the ground is good. Like you say, maybe the dimmer switch? How do I test it??
 
OLD CT

OLD CT

Well-Known Member
Most likely burned out like the old headlight, running without a good battery will do it.
It's easy enough to pull them out to check them.
 
cjpayne

cjpayne

Well-Known Member
You can use the continuity tester on the dimmer switch too.
There is a wiring diagram for the K3 in the Resources/Links section.
 
W

WENDELL OLDHAM

New Member
update: i replaced the hi/lo horn switch. no progress. still, my brake and tail lights work. when i turn on my turn signals both right and left front turn signal both light up but don't blink. i do not have rear turn signal hooked up. my turn signal indicator lights up. my head light will not come on. (i have tested the new bulb, it work on hi and low beam). 1 out of 3 bulbs in my speedo cluster works if a ground it to another bulb.
any help would be appreciated. i'm about ready to buy a new main harness as i believe the rats chewed up more than i can see
 
6

69ST

Well-Known Member
The old bimetal flasher relay needs full voltage and current draw (amperage) to work. Without everything in the circuit working optimally, it will never flash, period.

HL power is only there while the engine is running, unless you rig a power supply using test leads/jumpers.

Sounds like you're missing a ground at the HL end of the harness. Based on what you've said, I'd pull the harness, test the continuity of every lead and completely unwrap it, if there's visible damage to the factory sheathing.

FYI, lead breaks between the frame grommet and HL shell are very common and can be tough to diagnose as the leads can appear to be intact and even test okay...intermittently. Wire harness diagnosis & repairs are much less daunting with the harness on a bench, rather than in-situ.
 
W

WENDELL OLDHAM

New Member
thanks.
this was a barn stored bike in sturgis south dakota and rats had a nest where the coil goes. i repaired the harness damage that i could see but have probably missed some.
 
6

69ST

Well-Known Member
With rodent damage present, all bets are off, until/unless you verify each lead...on the bench. Repairing the damaged leads is straightforward, if you have a little soldering & splicing talent, basic stuff...more tedious than anything.

Of course there's always minty-new reproduction wiring & electrical parts...
 
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