This is a typical centrifugal start switch assembly.
http://www.powertransmission.com/iss...08/butler1.jpg
As the motor comes up to speed the washer on the left side pushes the
starting switch contacts open.

Start capacitors are for intermittent duty only, i.e. starting the
motor.
Values run from 100-300 MFD and voltages need to be in RMS, not DC
volts.

Jeff