Rev counter playing up and battery over charge

[mobil1]

Would this be connected to each other.
My rev counter shows the bike is ticking over at just over 2000rpm but its not. The tick over sounds about right.
It started doing it randomly but has not decided to stay at 2000.
When I rev the bike the needle shoots up and in the red and sometimes hits the stop.
The battery is showing 15.6v at tick over and 16.6 if I rev it to about 5000rpm. The lights go bright too.
I have changed the alternator but it has made no difference.
Any ideas would be great. Thanks

[nikko1968]

http://www.exup1000.co.uk/phpBB2/viewto ... fault+code

previously talked about....