87 force 85hp question

[bigblueny]

I have recently purchased a boat with a 87 force 85hp motor. The previous owner told me it would not start and the compresion in one of the cylinders was off. I decided to pull the head off and inspect the gasket, piston and cylinder. The gasket apears to be worn and there is a good amount of carbon build up in one cylinder, and on the tops of all the pistons. I am planning on replacing the gasket and spraying in some sea foam to start. Could this be my problem? Any other sugestions that I can try would be highly apreciated.

 

[JUSTINTIME]

Re: 87 force 85hp question

could be

 

[bigblueny]

Re: 87 force 85hp question

thanks for the insight :/

 

[Frank Acampora]

Re: 87 force 85hp question

Engine will not start covers a lot of territory. So basically, you need to check all systems. Any engine is essentially an air pump. If it gets air, fuel, and spark, unless something is drasticly wrong it will start and run.

So, logically, since it is the easiest system to check, inspect the air system. Check the reeds to be sure there are no broken petals. this ensures that air inducted into the engine stays there. Next check the entire fuel system from the tank right on up to the carbs. See other posts for details. this ensures that there is fuel to the engine.
Next the most difficult system--The ignition. Check the switch and wiring then crank over the engine to check for spark. You will definitely need a Clymers or other repair manual.
Read other posts on this system.


If you have air, fuel, and spark, then address the piston and cylinder problems. As long as the cylinders are not scored they should deliver decent compression after treating with seafoam. the trick here is equality: if all cylinders are equal but a bit low in compression, as long as its not too low, it is acceptable. and definitely replace the head gasket. $26 at WISECO.

So work slowly, use logic and think about what you are checking: you will be able to correct most problems

 

[eurolarva]

Re: 87 force 85hp question

Seafoam is a good preventitive thing for carbon but from your description I doubt seafoam alone will remove the amount you described. If you have the head off get some marvel mystery oil (wallmart sells it) and soak rags with the rags sitting on the carbon. Let this sit overnight keeping the rags wet then go after the carbon with a popsicle stick to remove the thicker carbon deposits. I would get a new head gasket and put it back together again. Describe the way the spark plug tips look. If motor wont start after you get it put back together again you will want to do a compression test. How far you want to go with this motor is based on your wallet, your aptitude to work on small engines and the ability to read and understand service manuals. If you have questions or problems continue to post here and someone will try and help you.

 

[bigblueny]

Re: 87 force 85hp question

Here are some pics I took of the head and cylinders, after I started to clean with the magic mystery oil.