Briggs & Stratton 400000 Operator's Manual page 14

Category C = 50 hours, Category B = 125 hours, Category A = 300 hours
For engines greater than 80 cc displacement and less than 225 cc displacement:
Category C = 125 hours, Category B = 250 hours, Category A = 500 hours
For engines of 225 cc or more displacement:
Category C = 250 hours, Category B = 500 hours, Category A = 1000 hours
80106344 (Revision A)
14 BRIGGSandSTRATTON.COM