Well, I've not seen this on the board before and a search yielded nothing similar, so I'm hoping someone can help. My tachometer looks to be reading about 2k high relative to what I believe the actual RPM is (the latter based on knowing the sounds of the engine at different RPM). So when it indicates I am at 12k RPM (redline), I'm pretty sure I'm only at about 10k - no way am I at redline anyway. When it says I am at 9k, where there usually is that sound of coming on the pipe, it feels like I am at about 7 - 7.5k. I know the sounds of the engine well enough to know the RPM reading is off, and just to complicate matters, this seems to be happening on an intermittent basis, so sometimes I'll go 50 miles and it will be fine. If there is any pattern, it is that when the RPM readings are too high, they stay too high continuously until I shut the bike off. On re-start, it may or may not start reading accurately, but if it is in accurate mode, it stays fine until I shut the bike down again, i.e., the intermittent aspect so far is a function of starting and restarting, not within a given running of the engine - not sure that is clear.

I checked around the tach for any signs of chaffed wires (none obvious) and cleaned up and tightened the ground, with no apparent effect. The engine seems to be running fine, even when the RPM is off. So can anyone suggest what else to check and the reason a tach would read high? Thanks for any help.
_________________
-Jim
'93 MC21