check how much power you got going to the tach if there is not enough then it start to jump as the needle goes up. My autometer did it and i asume it will cause the same on urs
ok ill check that, what if i were to hook it up to the positive side of the coil what would happen? I also have the stock coil still, could it be causing anything?
nope mine still does it, i grounded mine to the negative on the battery. only does it above 2000 rpm, if i go full throttle it seems pretty steady. I might look into an Msd tach filter.