The 80 HP engine seems to go on for ever but there appears to be a batch of camshafts on the 100 HP engine that turn to swarf at 1000 hours or thereabouts. I have come across a couple of cases and a BMAA inspector of my acquaintance, a couple more. Rotax have been good about crediting the unused "expected" life against a new engine but it ought to be borne in mind.