I would like to slow my electric motor from 1425 RPM to 175 RPM the driven pulley I have is 14" diam can anyone tell me what size drive pulley I would need

This may work (note that you have to select which value you want to compute):
Pulley and RPM Calculator | Engineering Information - Culver Armature and Motor (http://www.culvermotor.com/Engineering-Formulas/Pulley-and-RPM-Calculator.html)

This may work (note that you have to select which value you want to compute):
Pulley and RPM Calculator | Engineering Information - Culver Armature and Motor (http://www.culvermotor.com/Engineering-Formulas/Pulley-and-RPM-Calculator.html)

Many thanks have now sorted the problem.

Excellent.