1968 Evinrude Big Twin, Big Twin Electric, Lark 40 HP Outboards Service Manual, Page 55Get this manual
BREAK-IN sure that when engine is returned to service after an overhaul, the owner is advised to foHow break-in procedures exactlySee inside front cover and owner for correct fuel mixture
For the first to 10 minutes, operate engine at fast idleCheck operation of water For remainder of first hour, do not operate engine over 3000 rpm (approximate) or one-half throttle proximate)634 4