1998 Yamaha 25J, 30D, 25X, 30X outboards Factory Service Manual, Page 110Get this manual
ASSEMBLY AND ADJUSTMENT
4Install pro eller th pro eller sh aft, ith th fro nt sid facin ack ard, fit th ut and tig hte nPropeller nut: Nm (0.5 kgf, 3.6 ft lb)
5Slo ly turn th driv sh aft in and ut, and re th dial-g th driv sh aft sto ps in ach directio n6If th asure nt is in th ra 0.70 to 1.00it ill ecessary to or re shi s7If th asure nt is less th 0.70 m: (0.85 asure nt)2hickn ess of shi m(s) to incre ase If th asure nt is ore th 1.00 m: (M asure nt 0.85)2hickn ess of shi m(s) to ecre ase dStandard backlash (reverse gear): 0.701.00 mm (0.0280.039 in)