1966 CB77 Speedometer

dragonfly888 · Post by **dragonfly888** » Sat Oct 25, 2014 10:53 am

Hi:
I just bought a 1966 CB77 and the Speedometer has issues with the Tach. It just spins when the bike is revved.

First, the Speedo is not original to the bike, as it is an earlier one, where the Tach is clockwise and the Speedo is counter-clockwise.

Speedometer itself seems to work.

The question that came to mind is... Are the two speedometer types (1961-1964 & 1965-1966, I believe) interchangeable on the CB77?

Thanks for your help!

Regareds,
Kevin.

G-Man · Post by **G-Man** » Thu Oct 30, 2014 1:31 am

Kevin

I've not stripped the later type speedo but, if the speedo needle rotates the opposite direction, then the speedo gearbox at the wheel must be different. It's likely that the speedos ar not interchangeable without th drive gearbox.

Could you explain a little more about your taco problem where it just spins. Does it go straight to the stop, or does it fluctuate back and forth.

Whatever it probably means dirt or corrosion in the magnetic drive cup. This is a picture of the inside of a speedometer but the aluminium cup provides a sort of 'friction drive' against the spring. The two halves of that mechanism - cup and magnet must be clean with an air gap between them.

G

davomoto · Post by **davomoto** » Thu Oct 30, 2014 1:26 pm

Graham,

Right you are! You must change the speedo drive unit if going from an early to late unit or visa versa.

Davo

dragonfly888 · Post by **dragonfly888** » Mon Nov 03, 2014 11:40 am

Thanks for your replies, gentlemen.

I just wanted to point out that the Speedometer seems to be functioning correctly. This is on the right side of the unit. It runs Counter-Clockwise in earlier units and Clockwise in the later units. I am trying to find out if there was any sort of gear change to allow for the proper functioning of the Earlier Speedometer on a Later Bike (as is the case on my bike)

The Tachometer, which is where I am having the problems, ran Clockwise on both the earlier and later units. I am unsure why there would be a need for a gear change if there was no change in the direction ?

The Tachometer Issue: It just spins slowly around, clockwise, if I remember correctly, when the bike is revved.

Thanks for your help!

LOUD MOUSE · Post by **LOUD MOUSE** » Mon Nov 03, 2014 12:47 pm

No change for the tach drive.
I trimmed the bottom of a aluminum can to 3/4 inch and put 30W ND oil in there than positioned the threaded area in the oil for a couple of days. .............lm

dragonfly888 wrote:Thanks for your replies, gentlemen.

I just wanted to point out that the Speedometer seems to be functioning correctly. This is on the right side of the unit. It runs Counter-Clockwise in earlier units and Clockwise in the later units. I am trying to find out if there was any sort of gear change to allow for the proper functioning of the Earlier Speedometer on a Later Bike (as is the case on my bike)

The Tachometer, which is where I am having the problems, ran Clockwise on both the earlier and later units. I am unsure why there would be a need for a gear change if there was no change in the direction ?

The Tachometer Issue: It just spins slowly around, clockwise, if I remember correctly, when the bike is revved.

Thanks for your help!

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1966 CB77 Speedometer

1966 CB77 Speedometer