|Cali-Tach transfusions for Jackal Owners
Jackal owners wishing to fit tachometers can use second-hand Cali ones, but a simple re-wiring might be needed. Here’s what I discovered:
Because the Cali tach I acquired for my Jackal was from an FI model (albeit with an earlier P8 ECU rather than the Jackal's M15), and the connector was identical and the wiring colors matched, I assumed that the connection was the same - i.e. fed direct from the ECU, not from the coil as on carb bikes.
So when I got nonsense readings (rpm x5!) I thought the problem must be a difference in signal from the two types of ECU. This assumption was reinforced by various newsgroup messages about tachs for bikes with a P8 ECU not being compatible with the M15.
But then I saw a wiring diagram of a Cali with the P8 ECU and, lo and behold, the tach was still wired from the coil. This prompted me to re-visit some very helpful guidance from Carl Allison which I'd previously thought didn't apply to my situation. I ran a lead from the right-hand coil to the tach, leaving the ECU lead disconnected, and it works fine.
So the difference between the tachs isn't to do with different signals from different ECUs - it's whether the instrument is designed to be fed from the coil or the ECU. The problem arises when you try to feed a coil-driven tach with an ECU signal!