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I thought my tacho was optimistic ('86 R65) and yesterday checked it with one of those beaut non-contact tachos. When mine shows 4,000rpm it is really doing 3,300. I'm guessing a roughly 20% error is not normal. Can they be adjusted and, if so, how?

Cheers
Ray

Does that mean you can redline it to your hearts content, knowing that it isn't really?

I've heard that thos R65s are real revy, now I know why.

I was actually redlining to my hearts content when I thought the tacho was accurate.It turns out I was only doing about 6,00rpm. It has seen 8,000 on the tacho often enough though.

A while back the tacho stopped working. It turned out that a tiny spring like a clockspring had come loose from the peg it was meant to be attached to. I soldered it back on and the tacho has worked fine ever since. Maybe that upset somehow.

Cheers
Ray

I use a Speedohealer on my electronic speedometers (Suzuki SV1000 and Ducati S4Rs) to get them accurate. For speedometers, they have bike specific plug-ins to make it easy, but I'm assuming the tach processing isn't much different. You'd need to splice into your wiring. The unit does allow for a % change that you're looking for (negative up to 99.9%)

hzbloke wrote:A while back the tacho stopped working. It turned out that a tiny spring like a clockspring had come loose from the peg it was meant to be attached to. I soldered it back on and the tacho has worked fine ever since. Maybe that upset somehow.

That would do it... the accuracy of the tacho is dependant on the length and tension of that spring. If memory serves, there is a preset (potentiometer) on the tacho board that can be used for fine adjustment but I'm not sure whether there would be enough adjustment available. It may be that you could achieve a bigger adjustment by changing components on the circuit board but I wouldn't advise it unless you know what you're doing.

Rob

Thanks for the advice. I play around with that little spring when I can be bothered (or it comes away from the peg again). The meantime I'll just kid myself that the bike is revving freely.

Cheers
Ray