Topic: slow tach 400F

[tory b]

    I have a 1975 400F and the tach is super slow on it.
It does eventually climb and drop but so slow it is unreliable.

Is this fixable?And how.
Otherwise,I have another tach of another bike (not 400) that appears the same,but has a differant red line.Can I put a 400 gauge face on this tach to replace it?

[-CB-Jamie-]

I have the complete opposite problem with the speedo on my 400, it reads about 90mph when im actually doing somewhere in the region of 60-65mph. Wish I could get it sorted too.

Jamie