What year and how much HP is/does my motor have...?

There's two possibilities. the 1.6L was made from 1983 thru 1991 but there were also commercial numbers that begin with 98????? but I can't find the number you list. But if you check the year of the boat that might narrow it down, also the decals on the engine might give a clue..........Edit 12/15 your motor is a 100 HP. there's a possibility it's 110HP which was a small modification in 1989. But all major components are the same. It had something to do with "cross flow". I hope this helps.