Rpm signal jumping

[petters]

The rev counter on my bike has been jumping and falling out and beeing wild for a while now, and today I fitted a Koso and I still have the problem. Is there a sensor anywhere?

[darrsi]

Where is it jumping to and from, what rpm?

[petters]

Its all over, and sometimes when the enegine is not started, sometimes fron 2000rpm to 8000rpm and sometimes it shows nothing at all.

[darrsi]

On the right side of the carbs there's a Throttle Position Sensor (TPS), unplug it and see if the rpm needle becomes more settled, once unplugged it should go between 0rpm and 3000rpm.
If it does this in a controlled manner you may have a knackered TPS.


The black plug sits on number 4 carb with a wire going into it, you'll need a key or flat screwdriver to release the catch on it to unplug it.