Tachometer on or off?

[buzzstpoint]

81 xs400 Special II
my orginal tach had the hi beam indicator on it. But broken. I picked up a different tach that has the high beam and neutral indicator light.

I screwed the cable in, harness is different but doesn't concern me at this point. The rpm scale is different. Will these 2 tachs read the same? Meaning will I have correct reading off the newer tach?

I don't know what year the tach came from. Just picked if up from a cycle salvage yard.

 

[JARichmond]

Provided that the cable is the same, the readings should be the same. The way I see it, RPMs are RPMs. There is no usable unit of measurement for engine speed other than RPM. Give me until tomorrow, and I can have a reading for you so that you can tune your speed and your RPM, just to make sure they're right. Run by a "this is your speed" radar to confirm.

 

[buzzstpoint]

That would be help full if you could get a speed vs rpm.I don't know if there was a difference between the two TACHS other then visual appearance.

I have one of those radar poles just down the street in a 35 mph zone.

The rpm isn't too huge of a deal.just would like to know it the tach is reading correctly

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[xschris]

If the tach is off a yamaha of the same year or era the ratio will be the same. What was it off of?

 

[JARichmond]

Totally forgot about this. I know that in 4th gear, 4k RPM occurs around 30 mph.

 

[buzzstpoint]

In hunting around for a speed radar. The one by my house is now gone.