80mph speedometers.

[SteveD]

It's a 2.91, and mine is a 33:11 final drive. I knew that when I bought it. It'll still be close, and my current odo is way out. I also get another odo, a tacho and the case.

[grant81rs]

Gidday fellas,

I'm to busy just hang'in on to be worried bout my speedo.....

[SteveD]

Haha...I doubt you'd notice your tacho was kaput either

[Jean]

Oh well, so much for "ACCURACY".

[vanzen]

I believe they were on models during the gas crunch when the U.S. highway speed limit was 55 mph.
Don't know if it will break when you go faster than 80.

Gov'ment regs mandated the 80 mph clock in the U.S.

NO, they will not break if you go faster ... guaranteed.
My '81 3:1 RS with a factory clock was optimistically inaccurate by 5 mph at 60 mph.
Top speed at 118 – radar confirmed.

[Garnet]

"Top speed at 118 – radar confirmed."

And what did that cost ya?

[SteveD]

oops..double post..

[SteveD]

Oh well, so much for "ACCURACY".

If I'm using a 33:11 with the (140mph) 1.112 speedo ratio, verses a 33:11 with the (85mph) 1.078 speedo ratio, with the known inaccuracies as described by MS, which might be most accurate if compared to a gps? Anyone know mathematically?

Rear tyre diameter is 79.75 inches (203 cm) average of 3 full rotations seated on the bike. I guess higher speeds will cause some centrifugal expansion and lengthening of number???

[Duane Ausherman]

Look at how they are made. The only connection is magnetism via the cup limitor. No damage can occur from over speed, at least not to the speedometer.

[Jean]

Steve, since we ALL have different tires than the original, and the profile has changed quite a bit in the last 20 or so years...speedo "ACCURACY" is probably only a figment of anyone's imiganation. (I ran a 120 x 18 instead of a 4.00 x18 for a while, go figure!)
NOW, with the electronic speedos than can be adjusted, that's another story.