Tach troubles

[nichols750]

I bought my '78 750 about three months ago, it's my 1st bike and i love it, i have been slowly going through all of it, my current project is the tach. When i bought it the tach didn't work the po said it needed a cable, so i put one on now the needle just bounces up and down no matter how fast the engine is reving. any suggestion?? do i need a new guage?
thanks
mark

[GSstiny]

Pull the drive gear out of the head and make sure it doesnt have a broken tooth. Usually when a tach or speedo needle is bouncing its a drive problem rather than a gauge problem.

[nichols750]

SOUNDS GOOD.
how do i do that???

[bwringer]

SOUNDS GOOD.
how do i do that???

Like this:

http://bwringer.com/gs/tachcableseals.html

[nichols750]

i checked it out last night and the teeth all look good. so, what would be my next step?

[GSstiny]

Id take the cable loose from the tach and start the engine, just to be sure the cam gear is OK too. If you can see the end of the cable turning, it has to be the gauge itself. You can pick up one on fleabay or a junkyard, or try to fix it. Nerobro did a writeup on how to get into a gauge. You can also get in there by prying the metal ring off, but I havent tried it.

http://www.thegsresources.com/garage...ide_gauges.htm

I havent had mine apart yet, but Im told these tachs are just a little on the complicated side, so when you get in there, I wouldnt do anything except spray a little silicone lube and carefully clean out any blobs of dried grease.