Rev counter sticking?

[Slipperyeel]

Riding back from Mikeyboy's on Saturday i noticed my rev counter wouldn't rise higher than 4250 revs. When reducing engine speed it only slowly began to drop. Below 2500 revs it seemed to behave.

Is it knackered? Is there anything extremal from it that could cause it to misbehave? I did wonder if the dead moth I can see behind the glass had anything to do with it, but it's been there over a year!

Any ideas?

 

[Ian J Hartley]

It does sound like your tachometer is goosed. If a moth got in then God knows what else has got in, like moisture and corroded the electronics inside.

The tachometer gets its impulse from the motronic, but needs a positive 12v and Earth for power.

Just to the right of the headstock, just visible is a black 3 way connector. This is the Tacho connector. There are 3 wires feeding into this connector.

Pin 1 green/black +12v
Pin 3 brown Earth
Pin 2 black/grey signal.

It might be worth disconnecting the connector and checking for corrosion, and cleaning if necessary to see if that makes any difference, though I doubt it.

Ian

 

[Slipperyeel]

Thanks Ian. Sounds like good advice. Thanks too for pointing to the right connector.

Yes, if a moth got in there, it's unclear what else might have gotten in there!

I'll get the tank off Wednesday and report back