Which 3 cylinder Mercury do I have?

[MrSkiffy]

Just acquired a free Merc that runs. It's a 3 cylinder Serial # D000672. Decals are gone. Guy I got it from knows nothing. It's on my little 14 foot boat now and has only been run on muffs. Taking it out this weekend to see how it runs. He thinks it's a 50hp or 60hp from the 90's.

What do I have?

[CRH1]

Try this link, it might help you.

How to Read Mercury Outboard Serial Number | Boats.net

[MrSkiffy]

1991 50hp Mercury. It only weighs a little over 200 lbs! Thanks for the help. Did they make these for very long? Are they any good?

[CRH1]

I can't answer to how good those motors are. If its the 59 Cubic Inch 3 cylinder it can be made into a hot motor.

If you can get the model number on the tag, go over to boats.net and you can get a parts breakdown on the motor. That could help you some.

[VkingMike]

I think 1991 was the first year of this motor, they ran this version until 1996.

It's hard to go wrong with any well maintained mercury outboard.

[rhardwick]

Basically the same engine as the 65HP that came out in the early 70's.

[skialot2]

Serial # 0D000672 comes up as a 1990 50HP Mercury Electric start, Long shaft, Power Trim, Oil injection. (ELPTO)

[MrSkiffy]

Apparently the oil injection was removed. Would you think 50:1 would still be ok given its age?

[Onetime]

That’s a 49.8 cubic inch engine made from 1982-1991.
50 hp and 60 hp, which from what I can tell going through the parts links, the only difference between the two are the carbs.
Not a looper but a crossflow design powerhead but a good runner. They were replaced in 1992 by the 59 cubic inch looper design
The way they had oil injection was with the Autoblend system. The Autoblend was known to take out engines so you’re better off without it. Premix 50:1

[MrSkiffy]

Thanks! It's on a 14.5 foot fiberglass hull that weighs about #300 lbs. 20 inch transom. I'll be taking it out this weekend to get my RPM, MPH and motor height figured out. Prop is a 11 3/8X 14 pitch stainless. I see the recommendedrpm is 5500 max. Any danger/ benefit to taking it to 6000 rpm?