Speedo not working consistently ??

[C7YEA]

My speedo is not working consistently on a roadsport 175 - any ideas ?

I've tried adjusting the position of the speed sensor , several times, and can't get it to consistently work. It typically works to about 60mph, but then the needle starts to wave at me and then fails altogether.

Are the speedo sensors unreliable ? Any advice ?

thanks

[C7YEA]

Cheers DCL.

I'll have another go at adjusting as you suggest ...