Tom, had a small issue with the tach reading high a long time ago. When the motor was shut off the tach would not fall to 0. If it dropped to 1,000 RPM it would read high by that amount next time it was cranked ~like idle sounding normal but displaying 2,000 RPM. Not sure what I did or if it just corrected itself. Was recently discussed over on Trat. Severeal suggested cycling the key on, using the cut off switch with your thumb several times slowly. Worth a try. I rely on the cut off switch on the kickstand to shut the motor off

Do remember cycling the thumb switch and the problem went away sometime after.