The very same problem occurs with my CG-125's RPM Meter. It starts to fluctuate after 8k RPM ... jumps between 8-9 ... eventhough that happens occasionally, doesn't bother me. But i am only curious to know the root of this problem.
However, Speedometer remains stable even @ 120
I also discovered this problem on Long Route. I was going to Mananwala from Lahore. Was going @ 110-120 when discovered this problem. After a bit of observing, i noticed that needle only dances whenever i go over bumps on road. While at Stable Drive (on Clean Road with no bumps), no such thing happens.