tach question

[mark98012]

I have a '05 RK Classic, I have a small tach on the handlebars hooked up to the pink wire from the EMC. The same year's Road Glide's tach is hooked up to the serial buss (same as the speedometer), my question is: Are any of the smaller tachs run using the serial buss or the tach output? My idle rpm's seem right but not to sure at speed, I seem to be running 200 rpm lower than my old bike. Just wondering if anybody knows, I never had directions to hook it up with. Anybody hook one up to an '05 or newer lately?

Mark