Do I need surface gap spark plugs? Which one? 1984 Yamaha 50 hp

RandyJ

Master Chief Petty Officer
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Jun 13, 2002
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The spark plugs I've been using foul pretty easily because I troll a lot. NGK B8HS-10 is what NGK application shows and I'm a fan of NGK plugs. Supposedly "surface gap" .. what I call "rim fire" plugs are better for trolling and running WOT as many fishermen do.
If I replace the NGK B8HS-10 plugs with "surface gap" plugs which one should I use? I haven't been able to find a cross reference to help me out on this one.... I don't really care that much about brand names either. Normally I go with Champion or NGK on outboards.
 

robert graham

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Re: Do I need surface gap spark plugs? Which one? 1984 Yamaha 50 hp

I wouldn't stray from the recommended B8HS-10 plugs, but maybe a lighter gas/oil mixture(like 75:1)for extensive trolling would help some. For years I've used a Harbor Freight Spark Plug Sandblaster(about $15) to blow the carbon off all my plugs...works great and I rarely if ever buy new plugs for my outboards, mowers, blowers, cars, etc....good luck!
 

Silvertip

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Sep 22, 2003
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Re: Do I need surface gap spark plugs? Which one? 1984 Yamaha 50 hp

Try changing brands & type of oil. If you are not using a semi- or full-synthetic, try it. Better than ruining a motor by installation of an incorrect spark plug. In the past I've had far better success with conventional plugs vs surface gaps, especially in engines that run at slower speeds. There is no cross reference because the engine's ignition system was designed around a conventional plug.
 

Capt Ken

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Re: Do I need surface gap spark plugs? Which one? 1984 Yamaha 50 hp

If you will use a decarboning agent like Ringfree, it will keep the plugs and cylinders clean.
 

RandyJ

Master Chief Petty Officer
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Jun 13, 2002
Messages
808
Re: Do I need surface gap spark plugs? Which one? 1984 Yamaha 50 hp

Thanks guys. I always like to bounce things off of other brains to see what someone else is doing or would do. I know that because it's too inconvenient to buy gas on the water that we've been just putting in whatever we could squeeze into a 5 gallon gas can (usually about 5 1/2 gallons) then giving it 16 oz. of oil. Spark plug wires keep falling off and adding to the fouling situation. We're on the water year round and quite a lot so it's an every day thing much of the time. I like the idea of using the decarbonizing agent and like others I rarely install new plugs in anything but do need to get a plug cleaner (sand blaster) rather than just squirting with carb cleaner & using a wire brush but that has been working pretty good. Thanks again.... I probably do need to lighten up on the oil but I'm of the school that spark plugs are cheaper than power heads/cylinders....
 
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