Topic: Speedometer Variance

[HairyPotter]

The frame and engine on my bike indicate that I have a 1976 CB750K. However, the speedometer exactly matches the 1972 cb750K shown on the SOHC restoration guide.
http://www.sohc4.net/index.php?title=Image:72750KGuages.jpg

It seems as though when I ride, I'm going about 10 mph slower than what it feels and what it seems other vehicles are going. Is there a difference in gearing/speed ratios between speedometers of different years, specifically, 1969-1976? Is there a way to adjust the speedometer gear?

Also, in 5th gear going 80mph, I'm only at 5000 rpms. Is that normal?
Thanks

[andy750]

The frame and engine on my bike indicate that I have a 1976 CB750K. However, the speedometer exactly matches the 1972 cb750K shown on the SOHC restoration guide.
http://www.sohc4.net/index.php?title=Image:72750KGuages.jpg

It seems as though when I ride, I'm going about 10 mph slower than what it feels and what it seems other vehicles are going. Is there a difference in gearing/speed ratios between speedometers of different years, specifically, 1969-1976? Is there a way to adjust the speedometer gear?

Also, in 5th gear going 80mph, I'm only at 5000 rpms. Is that normal?
Thanks

The speedometers get less accurate with age so I wouldnt really trust it unless you know its not sticking and even then....going 80mph @ 5000 rpms is close enough to normal (in my experience). 60mph @ 4000 rpms (with stock 18/48 sprockets) is my usual gauge for "normal".

cheers
Andy

[kghost]

So you have the tripometer on top of the odometer?

You'll note that the 72 and below mount with a band....rather then bolted to the mount.

Later models had the odometer above the needle....tripometer below.

If your refering to the color of the gauge faces....some were blue some where green.


What RPM you read at speed is also dependant on what sprockets your running front and rear.

For example my 72 reads 4000 RPM at 70 MPH but it has a 40 tooth rear as opposed to 48

[HairyPotter]

The odometer is below the dial. But I see now that mine has different numbering than the '72 example.
I'm running a 18T/48T sprocket set. Sorry it's blurry...

[andy750]

You have K6 clocks I think - earlier ones the tachometer only reads up to 9000 rpm or something like that - doing this from memory - my K2 gauges are like this.

The "blue" faces that you have were likely green in the originals but time and sun has faded them.

cheers
Andy