Revs bouncing around

[The Novice]

I think the tacho on my bike is either faulty or wiring is broken/loose connection as the revs dont pick up on the tacho properly. Anyone know where does the tacho get its info from so i can trace where there might be a loose connection.

[Cammo]

It's usually to do with a loose earth wire.

Check that the earth (negative) wire at the back of the tacho is attached firmly, maybe take a look at all other earths on the bike also.

The tacho signal comes from the cdi, usually via a coil.

[The Novice]

will do , thanks for the info.