how to test tach wires ?

[steven polaski]

I have positive & negitive but how do I test the tach wire ? My tach does not read at all and was working a little while ago.

[steven polaski]

bump

[Early_S_Man]

Steven,

The connections at the 6-pin connector of the CDI unit [both the individual female 0.25" Faston connectors in the molded plastic connector, and the male 0.25" tabs of the CDI unit] should be cleaned with Brakleen [first, to degrease], 91% isopropyl alcohol, rinse with distilled water, then swab with 9% pickling vinegar [if available, otherwise ordinary 4% or 5% vinegar] ... rinse with distilled water and blow dry with compresed air. Crimp the sides

Continuity from TD terminal at CDI unit to TD terminal at tach should be confirmed with a multimeter ... less than five Ohms.

Check for pulse activity while engine running with CMOS logic probe, NOID [Baum Tools -- recommended by Bentley] or oscilloscope at 'TD' wire terminal while still connected to powered tach ... if non-pulsing, steady Voltage level in 6 - 11 Volt range present, expect D8 in the CDI unit to be blown. D8 is a very common 1N4148 switching diode, available even at Radio Shack!

Engine shuts down

[steven polaski]

Is there any benefit to an msd unit and is a autometer tach compatible with a cdi unit ( I ask these questions because it's not often I have you earlys s man around ) !

[steven polaski]

hello