Bore Size

[Airmandavis]

Is there a way to tell what Bore size you have without removing the head? It is a 50 hp Force. I know It can be 3.312, or 3.375. Thanks Zach

 

[pnwboat]

Re: Bore Size

Sometimes you can tell depending on what year, but to be 100% sure, you have to take the head off and measure. Especially 1989 - 1990 motors. They used both sizes during that time frame.

 

[Faztbullet]

Re: Bore Size

Find out the year as this will get you close to size, better to measure it anyway just to see if has ever been bored.
1981-83............3.187 bore
1989-90............3.312 bore
1990-98............3.375 bore
1990 was year it could be either size

 

[Airmandavis]

Re: Bore Size

My motor is an 88. The specs in my seloc manual say that all 50hp Force from 84-89 Have a 3.1875 Bore. Also the only sized pistons that Max Rules, and Wiseco sell for the 84-89 50hp Force (with the exception of over-sized) is a 3.187 Bore. What confuses me is that Iboats.com, Sierra, and Mallory, only offer
3.312, and 3.375 as a standard bore size? They don't even carry the 3.187 that the manual calls for. I would go ahead and tear down the engine and verify the correct bore size, but I am currently stationed away from home. I would just like to have all the parts ready to go when I get home, But I may need to wait.