Rev Counter dead

[manxgprider]

Hi Guys,

I've just refitted a rebuilt motor into what is a race bike. The rev counter is dead. KIPS works as normal and engine runs perfectly. Have checked earth to the rev counter which is okay and have 12volts to the brown wire terminal. Not sure what voltage to expect on the black wire which I believe is common with the black/white wire form the CDI which also goes to the coils, but this has continuity from the rev counter right back through all connections to the cdi. I tried a piggy back wire from the black/white coil wire and still no rev counter.

So, am I safe to assume the revcounter is knackered? Strange as was working before the bike got stripped.

Any feedback appreciated

Cheers

Gavin

[ScottaKR]

A dead tacho is commonly caused by the voltage regulator failing causing the voltage to go well past what most of the electrical system was designed for, or can handle. Before you ride the bike again, put a volt meter on the battery, and slowly bring up the revs. If the reading goes above 14.4v or so, shut the bike down imediately (before you cook the CDI) and get yourself a new regulator.

[manxgprider]

Hi Scott a KR

Checked the voltage and is not over charging, in fact the voltage seemed to dip as it revved?????

Gavin

[ScottaKR]

Hi Gavin,
If your voltage is dropping as you bring the revs up then you have an earthing problem. Clean and double check all your earth points, then check your voltage again.

[manxgprider]

Hi ScottaKR,

It all makes sense. The bike is no longer here, but I am getting a friend to check the electrics. The temp gauge was also under reading, just about off the bar when I think engine at full temp, so points to a bad earth (high resistance).
I believe that I attached the earth from the loom to the cylinder head when I am now convinced it should have gone to the frame.

Will let you know in a few days when it gets checked.


Cheers

Gavin