1981 750 C starter not engaging

[slash360-2]

Bike starts fine when it's cold, but after riding for a while (30 min.+) it may take 4 or 5 tries before starter will fully engage.Thanks in advance for your help. Steve in N.C.

[woodsrider250-2]

Bendix (starter) could be going bad, solenoid could be going bad, could be bad ground.