Speedo is out by 20kms

I've only had the ZX-9R for a week and noticed (after a few rides to work) that the speed I was doing and what was on the speedo was very different, thought that was strange with all these cars passing me especially the grey/purple haired ones. Anyway asked Julie to drive and I would follow her with the GPS on and do the speed limit in a few different zones and yes .......the speedo is out, thought it was the new tyres but it happened at every speed increment at the same difference (20 kms), so couldn't be that, as my car has different sized tyres than the manufacturer suggests and it goes out a couple of km's more as you go faster.
So my question is would a speed healer work and be the best to get to fix the problem if so what type?
Also does anyone have a gear indicator put on their bike like GIPro X-Type, is it of benefit to the bike and you?

Cheers
Steve

How many teeth on the front & rear sprockets mate ?
Should be as standard 16 F / 42 R...... anything else will affect the speedo as it's driven off the gearbox

Most of us 9 riders do drop to 15 Front as it gives a heap of front wheel airborn action but reads higher speed than actual which is probably what is on yours .... 20K variance does sound a lot for just a front sprocket though so maybe the previous owner went to 15 Front and a 44 Rear too ? Generally you'd only change one sprocket
A speedo healer will cure it....... Digigear indicator never had a problem counting up to 6 myself but others swear by them ?

I have 15/45 which results in about an 18% error (reads 118 when GPS says 100). You get used to it after a while, or you could use a speedo healer as Rossi's suggested.

A constant 20 km/h out is pretty weird. Never heard of that before.

Thanks for that, I have it in for a service at the local Kawasaki dealer and have found that it did have an upgrade on the front sprocket, how many teeth I don't know, but asked them to have a look at it and a few other things
Cheers

I've had the bike serviced and the speedo problem looked at and they've recommended that they can't do anything but fit a yellow box or a speedo eliminator, so if that's all that is wrong with my bike then that is good but have to give my credit card a rest before I spend any money on anything else

Mick C has one of those GiPro speedo thingy's.....its very accurate. You could get details by sending a pm to him here or at cR ...

Mick C has one of those GiPro speedo thingy's.....its very accurate. You could get details by sending a pm to him here or at cR ...

Cheers Gos I'll do that