The Koso digital rev counter I'm using on my Super Monza is very erratic!

I'm powering the backlight by a battery and wrapped the pick up wire around the HT lead 4 or 5 times.
I've always used analogue rev counters (Pitsch/Krober) - which were brilliant - but don't think you can get one of these to work with the Varitronic (and don't like the look of the Scitsu) so sort of stuck with the Koso (which wasn't cheap!).
Anyone else using one of these digital rev counters, and found out how to smooth out the readings?? It jumps all over the place within each thousand range (if that makes sense), so really does make it hard to read on the move!

Thanks,
Tom

Ps. also need to add, I've set it at 2-stroke (rather than 4-stroke) and 2 pistons (for the Varitronic 2 sparks) in the set up, which I think is all correct?!
