I've used the search function and can't quite find what I'm looking for. I restored a speedo and tach for a project bike ('74 CB750) I'm working on. Everything with the bike is pretty much buttoned up, running and riding.
The tach while the bike is running seems to be off by about 1,000 RPM exactly. I have 3 CB750's and have ridden them quite a bit, so I have a pretty good idea by "sound and feel" what the RPM should be. When the bike is warmed up and at a good idle, the tach is at 2,000 RPM. While riding, you reach the redline very quickly when I know from riding the bike that the motor is not spinning that fast.
It is not the original tach, i pulled a different set that were in better condition. Do the tach's have different ratio of drive gears in them? Could i just have a set with a different ratio?
