Any difference between 90 and 91 50hp Merc (2 stroke, 3 cyl)

[CLYENSS]

My 50 hp Merc is a 1990 (s/n OC294896, 2 stroke, 3 cyl).

I have the service manuals for

MODELS 40?50?55?60
With Serial Numbers
United States - 0G531301 and ABOVE . .

and

MODELS 45 Jet ? 50 ? 55 ? 60
With Serial Numbers
United States - 0D000750 and Above . . . . . . .

This second one is for models starting in 1991. Will this be OK for my 1990 outboard or should I get the previous service manual that covers OC294896. I think that manual was first published in 1977.

Second question: low compression in one cylinder (90, 120 and 120). Ran the PowerTune through the carbs already. Cylinder one went up from 80 to 90, not high enough. Is it worth paying for a rebuild or am I better off upgrading.

Thanks

 

[outhere99]

Re: Any difference between 90 and 91 50hp Merc (2 stroke, 3 cyl)

I have an '86 50hsp 3 cylinder. It seems everything for it is for the years 86-90. The manual I have (Seloc, very vauge on everything!) discusses differences from 90-91. So you might want to look into another book.

If all you have to do is hone and replace rings I'd stick with what you have. An "upgrade" could cost several thousand dollar if you mean replacement. Another used engine could put you in the same boat (no pun intended).