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    Major Power loss

    Today: Had a great day out on Lake Jesup - Orlando FL. (Caught 16 speckled pearch before the cold front moved in). Have a 1987 25hp Mariner. On the way out, every time I would attempt WOT it would sound like the prop was out of the water spinning and experienced major loss of power (which...
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    Trolling motor sunk

    I had a silly thing happen to me today. My Minnkota trolling motor popped off the mount and sunk to the bottom of this shallow lake. (don't ask how) NOW I didn't have a mask and/or snorkel to dive in and find it at the time but I do know generally where it's at. Question is this: Is it worth...
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    Where is the high speed jet?

    Quick question... I have a 25hp 1987 Mariner. I checked the schematics and I cannot find out which jet is the "high speed jet". When I pull my carb off there are two jets where gas can come out - there is a wide one and a very small one. Is the small one typically the high speed jet or vice...
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    Seafoarm Decarbonizing... Overheating WOT????

    Hi guys, So I did the seafoam deep decarbonizing on my 25hp 1987 2-stroke Mariner #0B211923 hoping to increase compression (psi). I did the whole 1 gallon of gas/oil mix and one 16oz can of seafoam in a small auxillary tank and threw the earmuffs on it and ran it on and off for about 15 min...
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    Where is my thermostat?

    1987 25hp Mariner Serial#0B211923. Where is the thermostat? I don't think I have one. Took my exhaust manifold off looking for it... wasted two perfectly new gaskets on the witch hunt. Please help anybody... Nick
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    Piston Rings

    I have a 1987 Mercury Mariner 25hp 2 stroke 2 cylinder serial#0B211923. Runs good, clean carb everything is "OK" HOWEVER - I don't want an "OK" motor. I want a POWERFUL MOTOR!. I think the guy that had this motor before me ran it into oblivion and it could probably use some new rings right...
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    Tachometer???

    OK.. I got a 25hp 1987 Mariner short shaft. Run's great. Considering getting a higher pitched prop for better high end speed. Need a tachometer to know where I'm at with my current prop vs the new prop. Want to do some calcuations and what not. I would also like to mount it to my steering...
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    Idling

    Hello all, RE: my 1987 Mercury Mariner 25hp outboard: What I'm finding is that my engine idles perfectly in the water when I first launch. Then after I open it up and run it a few times around the lake it starts idleing very rough and will konk out and idle rough for the rest of the day. Why...
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    Gasket dressing???

    Hi guys quick question: The gasket between my carb and the engine block is shot. I have to replace it with a new one. I want to be sure it has a long lasting life. Is there any sort of "dressing" that I can put on the gasket (i.e. grease, transmission fluid, oil, no-ox) that would give it a...
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    My ENGINE DIED TODAY!!!

    1987 25HP Mariner 2-stroke Manual start Ok so here goes the story. Yesterday cleaned the carb jets, new float,... etc... Earlier today put the ear muffs on and sprayed almost a full can of seafoam through the carb on and off for about an hour. Tons of smoke - good stuff. Had better idleing...
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    Spark plug wires!!! Pls answer quick

    Hi guys I'm taking my boat out tomorrow and would like to complete some basic maitenence on my 1987 25hp Mariner serial# 0B211923. I'm trying to swap out the spark plug wires bc the guy before me said he had to cut the boot off bc they were arching to the plug. Now it's arching to the COWL...
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    Piston Compression...

    Mariner 25hp 1987 Compression What I'm looking for is what is the ideal compression for my engin model. I just want to know how far off I am from the norm. For example if I brought my engine to a shop and the mechanic with 40 years experience checks the compression, he has a number in his...
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    Carb Kit for 1987 25HP Mariner

    I have a 1987 25HP Mariner manual start my serial number is 0B211923 and the Mercury model # is 7025207. I really have had a difficult time trying to track down the carb kit for my motor. I'm in great need of a carb rebuild (don't think it's ever been done). If anyone can tell me a model...
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    Mariner 25hp 1987 Handling

    Hello, I?m new to the outboard motor community. Used to have a Seadoo jetboat? was in the shop more than out to sea. I now have a Mariner 25hp 1987 on a 14ft aluminum v-hull. Can someone please help me with the following problems: 1.Engine is loud. I hear the air intake along with a lot of...
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    Mariner 25hp 1987 Compression

    Does anylone happen to know what the piston compression should be on a Mariner 25hp 1987? You know when you pop the spark plugs and attache a pressure meter and give it a few pulls?.. Just looking for the PSI that it SHOULD BE. :-) Many Thanks
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    Please help Mariner Outboards

    Hi guys, I must apologize for adding to the multitude of posts asking for the year of their Mariner. HOWEVER I have searched the internet for days and maybe I'm using the wrong keywords - I just can't crack it. I have also read about 1,000 threads on and I cannot find where someone leaves a...
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