internal gear ratios on fmx and cruise-o-matic

[662doorgalaxie]

I put 3.00 gears in my gal and and used the speedo drive gear out of an FMX

with 3.00 gears and I am reading way slower than actual speed. Do I need more teeth, or less? It has a red gear with 16 teeth currently.

[R Pope]

You have to make the speedo cable spin faster, so a smaller driven gear is needed. Figure your speed error as a percentage and get a gear that much smaller.
What was the original gear ratio?

[662doorgalaxie]

3.50 ****************