Confused 115 in a 90?

I bought a boat today and the outside of the engine says it is a 90hp but the serial number says 115 hp. The guy said it was a 115 hp engine. The serial number on the powerhead is 4313852.
Can you put a 115 in a 90?

Re: Confused 115 in a 90?

there are a few reasons this could be the case.1)its a "frankenmerc"motor.Simply stated,someone built the motor from parts of other motors.2)the"need for speed" kicked in and so they put a 115 on it and changed the decals to follow the recommended hp rating of the boat.Is it rated for 90hp max?Or 3)and Im not sure of this but block may be the same for yr range in question.Maybe he blew the 90 and since block was the same he just used a 115 block to save money(found one cheap).No matter what the reason for this,I sure hope you water tested the boat/motor before buying.Lots of "mercury wizards"out there but VERY FEW know what theyre doing.Hope it wasnt someones"hey,Id like to rebuild a motor to see if I can"project.Not saying a newbie rebuild is out of the question as possible.Just hope its the decal scenario,for you.

Re: Confused 115 in a 90?

Maybe they changed the cover.Some people manage to drop them overboard.J

Re: Confused 115 in a 90?

jerryjerry05 said:

Maybe they changed the cover.Some people manage to drop them overboard.J

Click to expand...

Or forget to put the pins in the ski pylon. (don't ask)

Re: Confused 115 in a 90?

The serial # you posted is a 1976 "inline" motor and the 90hp didnt hit the market till 1978. They (90/115) will interchange as they use the same midsection and gear ratio, so it is possible the 90 "popped" and a older used 115 powerhead installed to get it back on the water. The wiring had to be modified to use the 115 as it is a 'battery CD" ignition and 90 hp were ADI ignitions...

Re: Confused 115 in a 90?

Got it figured out...it is a 115 hp but someone put 90 hp decals on it for the boat it was on before.
New problem. My mechanic cleaned out the carbs and it ran like a top. I go to pick it up today and it ran for a bit then cut off. Cold start. When we tried it again it just turned over but no spark at all. He said it was it was a bad trigger.
My question is... Is it worth putting money in this old engine? I bought the boat, trailer and engine three days ago for 800.00. It is a 94 Avenger that needs seats and carpet and 2 lids. Ha ha and a new motor. Lol
I have 100.00 in my mechanic for a total of 900.00.

Do I put it back on craigslist and get my money back or deal with the headache of a 1976 engine?

Re: Confused 115 in a 90?

A trigger is easy to replace, buy a lifting ring and an OEM manual and you can do it yourself for $200 bucks. These motors are very easy to work on yourself. The I-6 mercs are some of the most simple engines to work on but they do have their quirks. All depends if you like to get your hands dirty.