| Had the same thing with the 748, turned out to be a loose earth connection on the battery!
Everything else worked fine except the rev counter which fluctuated badly. I think the loose connection was causing sparking as the battery vibrated in the battery tray while the bike was running. As the Superbike tacho works of a pulse, this was probably over-riding or confusing the tacho and that's why it didn't work. I just tightened up the battery connection and it worked fine. Must have been when I fitted the connectors for the Optimate ... maybe if you removed the battery you have the same problem? | 
antonye
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