Looking for guidance on honing scored cylinder wall on Mercury 115

StarcraftSF

Recruit
Joined
Jun 10, 2018
Messages
3
I have a 2004 Mercury 115 Optimax DFI 2 stroke inline 3 1.5l outboard. I aquired this motor used with the middle cylinder with no compression, upon removal the rings were seized as thought. My question is regarding the middle cylinder wall, it is scored but not sure when a cylinder is beyond honing, really dont want to get into over boring or replacing sleeve if thats even possible. Ive read that a ball hone is what i need? Do i need to chamfer the port edges with some kind of grinding stone after honing, ive added a photo of the cylinder wall scoring, hopefully someone can tell me if i can bring it within 10 psi of the top and bottom cylinder which look great and have great compression, also is there anything else i need to replace besides the middle piston, rings on all 3, and top and bottom crank seals? I read somewhere about replacing the connecting rod bolts? When i pulled the oil tank a balled up piece of plastic came out which i beleive was constricing oil to the pump causing my issue with the middle cylinder but if anyone else has an idea what made it fail id love to hear, the water pump was in good shape.
 

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oldman570

Lieutenant Commander
Joined
Mar 25, 2011
Messages
1,615
Honing won't fix that !!----It needs to be bored.

Time to dig deeper into ones pockets for a sleeve, rings, gaskets, and new piston , in order to get the motor back to running correctly again.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
14,118
Time to dig deeper into ones pockets for a sleeve, rings, gaskets, and new piston , in order to get the motor back to running correctly again.

I doubt sleeving is needed for that bit of scoring
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,937
That cylinder needs bored over size as min as possible.The reason you do this is there is no way to richen up cylinder mixture .WSM makes a .010 and Merc is .015 oversize and it wont clean up at .020 max it will need to be sleeved. It will need gaskets/rod bolts/impeller/,and figuring out what caused it to fail as it wasn't the oil pump blockage as other cylinders would show oil starvation also.Problems to look at are ECU an injector's(air and fuel)
 
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