Topic: Tachometer Cable Smoking???

[Mike.n.Ike]

Hey guys, have a little problem here, just this morning she decided to not start.  I pulled the plugs, plug wires, checked the battery, and every thing seemed fine.  I was getting a solid blue spark off each plug.  After a couple more attempts with the electric starter, I noticed the tachometer cable smoking about 2 inches away from going into the tachometer. Which puzzled me because this wasn't a electrical wire, but this was a white smoke so i concluded that my problem was a short in the tachometer instrument light.  I called my all knowing and very reliable Honda mechanic here in town and a smoking tach cable was some thing that he had never heard of before.  He came upon the same conclusion and that this electrical short could be draining enough power from the ignition system to prevent start up. 

Has any one else had a similar problem??  If so what is the solution here?

Thanks

p.s. "she" is a '72 750 with dyna coils as well as a dyna S ignition

[scottly]

After a couple more attempts with the electric starter, I noticed the tachometer cable smoking about 2 inches away from going into the tachometer.

SWAG (Scientific Wild Ass Guess) is somehow your tach cable is acting as the ground to the electric starter. You need to have a solid connection from the battery - terminal to the motor.

[FunJimmy]

Did you recently install a HOT cam?

[Mike.n.Ike]

scottly -- Ha! The grounds seemed pretty secure when i gave a quick check before checking the timing.  Guess i should double check to make sure though

Jimmy -- No, i have replaced the cam but did not upgrade

[Old Moe Toe]

Have heard of this sort of thing happening after a frame has been powdercoated/repainted. If the earth lead does not earth onto the frame(which it wont unless you make sure of it) it will find other avenues for earthing. Have also heard of clutch cables melting for the same reason.

[LesterPiglet]

Hmmm, possibly your cranckase vents are blocked and the gases are being forced out the tacho connection? Any oil around there?

[martin_uk]

+1 on cable possibly  acting as ground.

You can use a volt meter to check volt drop on negative/ground circuit.

Just connect lead to negative battery terminal and other to engine.

The volt meter will show the volts going through meter rather than high resistance on normal route.

http://www.autotechnician.org/starter-voltage-drop-test-explained-in-plain-english/

[Rgconner]

Too many tachyons.

[Mike.n.Ike]

Hey guys, thanks for the numerous replies! 

I got a volt meter to check the grounds and sure enough the ground coming right off the (-) terminal was partially touching the frame.  The other ground seemed secure.  She started right up! 

Im a little weary of the partially cooked tach cable now so im going to replace the cable just to be safe.

Thanks a for the suggestions, i appreciate it!