I'm stumped with this one, the bike is riding fine but the rev counter reads between 3-5k over what the engines actually doing. When i'm accelerating hard (i.e. high revs) the needle just sits at 17k. i've had up to 8k reading when its been ticking over....

It was abosultely fine until last week, just suddenly happened..

any ideas?

zxr400 L2 btw.

Try measuring your battery voltage whilst the engine is running, anything over about 13.5 volts would indicate the voltage regulator has decided to stop working. This will also boil your battery and make your lights exceeding bright.

Just measured voltages and it never went much over 12....So at least the battery acid isn't boiling. I think maybe the rev counter has just had it do you think??

I had the same thing on my R6 race bike, it was reading about 20% high. I wondered why I wasn't hitting the limiter and why was everyone passing me so easily on the straights!
Turned out to be a dodgy tacho.....

castrol101 wrote:Just measured voltages and it never went much over 12....So at least the battery acid isn't boiling. I think maybe the rev counter has just had it do you think??

It should be around 14v when the engine is above around 5k revs.
Low voltage would also cause a problem with your rev counter as well as high.

Odds are you've figured this out by now anyway as the battery is most likely to have run flat. New regulator / battery / both.