1999-2004 Honda TRX400EX FourTrax Service Manual, Page 157Get this manual
CRANKCASETRANSMlSSlONCRANKSHAFT
CRANKCASE ASSEMBLY
Clean the left and right crankcase mating surfaces thoroughly, being careful not to damage themInstall the dowel pins and new gasket-
Make sure the are in the left crankcaseInstall the right crankcase over the left crankcase