Custom Speedometer

[Windy]

Now then people, I’m cleaning up the bars on my 750 & want to fit a custom speedo. I’ve seen a few on eBay & some state ‘60mph = 2240 rpm’
They are mechanical & use the speedo cable.
My question is, would this be accurate on a 1982 CB750F?
Does the motor run at those revs at 60mph, in top gear I presume?
What do you think, anyone fitted a custom speedo?
Cheers, Windy

 

[amc49]

I certainly haven't but would point out that speedo drives off front wheel meaning the trans gear has no effect there. Tire size would.

The only way to know the rpm would be to figure the tire circumference against the speedo gear ratio at the front wheel, there is a gear-to-gear couple there..........

I went to Dennis Kirk and most there were digital and inferred speed rather than reading with cable, the few cable ones were for Harley.

 

[Windy]

Thanks AMC, I’ve since found out that it’s the inner cable that revolves at 2240 rpm at 60mph. I’ve just bought one that was fitted to a 1980 cb750 & worked ok ( mine is a 1982 F), so we’ll see.
Thanks again. Cheers

 

[amc49]

Should be close if worked on '80, the tire on an '82 is a bit bigger. And yes, I assumed we were talking about the cable rpm with my above answer.