tach not working....

[4DoorSi]

Ok, so I have a 99 M750 with road racing gauges.  The tach works intermittently.  Seems to be working properly less and less lately.  It started out not working when it was cold (below 60* outside), now it seems to not work most of the time. 

When it does work, sometimes it will just instantly drop from 5k or whatever revs I'm actually at to 0.  then it will jump back up and work for a while.  then back to 0.

I've noticed there seems to be a lot of play in the needle, it bounces around with vibration from the bike or bumps on the road.  When I say a lot, I mean like it will bounce about 300 revs on either side of the actual revs.

So, any ideas?  Anything I can check/fix easily?

[ScottRNelson]

That's common behavior for those tachometers.  On the one that I had there were three screws in the back that connect the circuit board to ground.  Loosening those screws then tightening them again will sometimes get you a better connection and smoother operation.  And sometimes there seems to be nothing you can do to fix it.  Mine jumped around between 4000 and 7000 rpms, but was smooth at lower and higher speeds.  I learned to ignore it, since it was good in the areas where I cared about the engine speed.

Maybe there is a good reason why Monsters didn't bother with tachometers for so many years.

[Spike]

I have a RoadRacing tach and not had any problems. I suggest that you check the electrical connections and the screws on the back that ScottRNelson spoke of. Your tach might just be done. Good luck.