Speedo Issues

[Spub]

The Speedo on my SFC reads about 25mph too fast. In looking over the parts diagram, I only see one part number for the speedo crown gear. Paradise shows the crown gear for a 750 with ND instruments is 25 teeth. There is a crown gear for sale on Ebay that states it is for a 750, but it states it is a 28 tooth gear, and says it is NOS stock. I can find no diagram that shows anything other than a 9 tooth worm gear. The Speedo has a Laverda logo, and appears correctly aged for being on a 1974 bike. Can anyone tell me the stock values for the crown gear and worm gear?

 

[Ernesto]

Hello, Spub.

You're absolutely right. The drive ratio for the ND speedo is 25/9,
like Andy states in his catalogue.
Never heard of a 28 teeth gear, the number he states is correct
for the 25 teeth gear. Maybe he just made a mistake when counting.
Your speedo would read even more if you used the 28er (if that's
possible  concerning the different tooth width)
I think workshops that overhaul instruments can adjust your speedo.
You would have to unscrew the cable at the speedo, roll the bike
for a defined distance and count the revolutions.
They will tell you.

hth, Ernesto

 

[Spub]

mille grazie, Ernesto.