1991 Force 120 Hp Outboard Problem with Cylinder #2

pnwboat

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Re: 1991 Force 120 Hp Outboard Problem with Cylinder #2

There is a gasket between the adapter plate and the block, but there is no gasket between the adapter plate and the lower end. Just silicone RTV sealant. Good luck with your "project"!
 

Force 120

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Re: 1991 Force 120 Hp Outboard Problem with Cylinder #2

Finally I got the block stripped down. The cylinder surfaces look good. No mark !!!
Here are measurement at 4 points: (2 top and 2 bottom)
Cyl #1: 3.3775; 3.3770; 3.3770; 3.3765
Cyl #2: 3.3770; 3.3770; 3.3770; 3.3765
Cyl #3: 3.3760; 3.3765; 3.3770; 3.3770
Cyl #4: 3.3780; 3.3775; 3.3765; 3.3765
Are they good numbers ? Does it need to rebore? or can get away with a honing job ?
Piston #2 is in bad shape.
 

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pnwboat

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Re: 1991 Force 120 Hp Outboard Problem with Cylinder #2

Well that's kind of a subjective decision. Factory manual says that maximum bore diameter for std. pistons is 3.3762. Looks like your cylinders are beyond that at a couple of spots. When I am faced with the same situation that you're in, I take it to the machine shop. I found a machine shop that really does a good job at a reasonable price. I let the machinist measure the cylinders and give me his take on what needs to be done. Then I look at my financial situation and the possible impact it will have on relationship with the wife. Sometimes the wife overrules the machinist LOL!

Bottom line is you might be able to get away with a hone job, one new piston and new rings. Hard to say how well it will run or how long it will last. I would guess that your would probably be OK since it's not too far out of the service limit. It was running OK before your little mishap right! Depends on what you're future plans are. Do you expect to keep it for a long time? If so, then my own personal preference would be to bore it w/new pistons. If you don't plan on keeping it, then maybe just hone and replace the one piston. It's up to you for the final decision. Everyone's personal situation is different so what works for me may not work for you.

NOTE: Which ever direction you decide to go, lightly chamfer the edges of the exhaust and intake ports in the cylinders to minimize the chances of a ring catching and breaking.
 

Force 120

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Re: 1991 Force 120 Hp Outboard Problem with Cylinder #2

Question for pnwboat
Machine shop has measured it and machinist said all cylinders were within fine line of spec. He said there were 2 options I could go with. Bore out 0.010" with new oversize pistons. Or either hone them and order new piston rings. The second option is more economical for me since I just order 4 sets of rings. Do you know where I can get these rings for old pistons?
 

pnwboat

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Re: 1991 Force 120 Hp Outboard Problem with Cylinder #2

Sent you a PM.
 

Force 120

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Re: 1991 Force 120 Hp Outboard Problem with Cylinder #2

Now I have the engine together and it is set up on the stand. I don't have the key switch with the engine. I can start the engine by jump the red wire (+) to yellow/black wire for the interlock switch. The starter turns on but I don't have spark. In Clymer Force shop manual wiring diagrams shows wire (white) from CD module to terminal block and the this wire goes to key switch and then to stop switch. Does this wire need to be supplied by 12 V to power the CD module ? On my engine there is not a white wire but a black/brown wire coming from CD module to terminal and this terminal label as STOP #1. Is it this wire is the same white wire in the manual ? My question is how to by-pass key switch. Which wire supply voltage to CD module ?
 
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