Tach Problem

[JohnE]

My tach doesn't work but I know it did work in the past. So I put on a spare that I have and it doesn't work either (I have no clue if the spare works anyway, since I bought it as a used part and have never seen it work).

The ground on the tach is good. The power wire into the tach has 12 volts, and so does the grey wire that splits off from the grey wire between the TCI and 2/3 coil. I tried a spare TCI as well with both tachs and still neither tach would work.

Is there a way to test the "pulse" (I'm assuming that's just the TCI cutting power to the coils) coming out of the TCI, beyond having power at the grey wire at the tach? The bike runs fine so presumably the grey wire is doing its job.

At this point I'm thinking both tachs are fried. Does that sound right? If so I guess I need to find some kind of aftermarket tach that would work good on a race bike. Any suggestions for one that would take the stock pulse from the grey wire?

Thanks!

[yamaha_george]

j,
the grey wire goes to zero when the plugs fire if memory serves and the Tach counts the drop outs for RPM.
I seem to remember that RR or one of the other Illuminati wrote this up and there was a reference on inspecting tacho innards also in the Forum. If the old grey stuff is right it is usually a set of resistors that burn out and can be replaced.

I hope some one else picks up on this thread who has abetter memory than I.............

[kilika2]

Illuminati........... awesome.

Chris