72 johnson 125 tach install

[conwaylale]

My boat has the original tach on it and pre wired. My 72' Johnson 125 runs great but im afraid im running too high rpms and need a higher pitched prop. I am just wondering were the signal wire goes on the motor. Ive heard that it goes on either one of the rectifier wires? is this correct. Any info on this is appreciated. Thanks alot. Conway

 

[R.Johnson]

Re: 72 johnson 125 tach install

If you open the control box, you will find a taped off gray wire. Use that. You will find a hole in the box to run the wire through.

 

[oldrudedude]

Re: 72 johnson 125 tach install

Ive heard that it goes on either one of the rectifier wires? is this correct.

Correct. On motor connects to terminal block at 4th screw from the left with the yellow/grey wire. The grey tach wire may be faded with age and appear almost white (like mine).

 

[R.Johnson]

Re: 72 johnson 125 tach install

Why not use the gray wire in the control box instead of running a wire clear back to the engine. It makes for a more trouble free installation. That's why the wire is there.