[Mr.Mazza]

I believe its normal for the amp meter to flick like this. At Idle on a single cylinder everything goes slow enough to physically see ignition cycles on the amp meter, combined with the firing stroke being every 2 engine rotations, you get this pusling visible on the amp meter.
Above 1000rpm it becomes a blur that the meter cant move quick enough (or humans eyes cant tell) and sorta points in a spot.
Aslong as you have it reading + at just above idle all is well.

[Ice]

~ my ammeter is still bouncing erratically albeit in the neutral to positive range now. I hoked a multi meter up to the back connection of the bikes ammeter and am reading a pretty steady reading, it bounces around by 0.05 - 0.1 V on the multi meter while the bikes ammeter sways from slightly below neutral to halfway into the positive range bouncing back and forth about 2 times a second.~

 Sound about right for idle. 

[Chasfield]

Bike ammeters are the cheapest moving iron type that dont have any self damping qualities in the movement, but are rugged. Your multimeter will be a moving coil type, which self damps nicely.

[pknopp]

All I know, as erratic as mine is, I put a new battery on this spring and I haven't touched it since.