Speedo tachometer variance

B

Burlysun

New member
Location
California
My 1971 gt the tach is very bouncy needle and Speedo shows way faster than the speed I believe to be traveling. Any thoughts?
 

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I use my phone as a GPS, and now I smile when I hear blokes say they were doing 180 and BLA BLA BLA. Looking at its speed display while doing almost 160 on rough back roads where you can get away with that is NOT FUN. Looking at that speed display and comparing it with the bike Speedo is REALLY NOT FUN. BTW the speedo is always well under the GPS speed reading by at least 10ks and more. Eyes on the road, not on the gadgets.
 
Smith speedo and tach are very stable if in good condition or serviced by someone with knowledge and skill.
Ask Wolfgang, he should be able to help you out.
Speedo can read to fast if you have the wrong gearing on the hub and / or the wrong speedo.
Have you counted teeth on gearing parts at the hub? does the speedo have a marking like 600 or 1000 on the back?

Gerald
 
The Smiths speedos have two different gear ratios in the drive aparatus in the front wheel
look at the speedo face, if original then.......
if you see a number in the lower portion of the face (where 6 o/c would be on a clock) ending in /600 then the front wheel ratio should be 12/15
if you see a number in the lower portion of the face (where 6 o/c would be on a clock) ending in /1000 then the front wheel ratio should be 11/22

that is for Laverda brakes, the Grimeca may be different, (unlikely for a thought to be 71 bike) I am not sure, and different again if you have discs or ND clocks, which I know you dont, its just for general knowledge of others, so shut the f**k up rivet pedantic counters.
CLEM
 
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