Why isn't my tach working?

[chipbutty24]

My tach isn't working. Cable, gauge and drive gear appear to be fine. I hooked my drill to the engine side of the cable and the gauge moves. The bike runs. I pulled the drive gear and it looks ok (pic below). The gear is solidly attached to the shaft. When I put the gear back in, it cannot be turned by hand as I expected. Any ideas? I have yet to open her up but wondered if anyone had run into this before. Thanks.

[jfman]

You might want to pull the valve cover to check things out.

[Mekanix]

First pic isn't clear but looks like the cam is striped.

if not. Put the thing back in and start the engine . It should rotate and not jump or stop rotating.

Put the cable on and remove the end from the tach. Does the cable turn ?

If so. maybe it just wasn't fully engaged in the engine or tach.

If not , its either the cable isn't touching the driver in the engine or the cable is snapped.

Either way push the cable in and see if it catches and starts spinning.

IF the valve cover is installed and the gears are not lined up properly they can strip, but both pieces would show damage.

Just because it wouldn't rotate just means you might have caught a tooth for a second.