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  1. #1
    drewman's Avatar
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    '97 Yamaha GP1200 help...

    I got a 97 GP1200 from a buddy as a project and as I've gone taking it apart it doesn't seem to look like what's in the manual. I knew somethin was up when I noticed that the spark plugs its supposed to have are NGK BR8HS but it had NGK BR8ES's in it which are a much longer plug and fit perfect. Can anyone tell me what kind of engine I got or what I'm lookin at exactly? (pic attached, more to come if you need more info...)
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  2. #2

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    It appears to be a 65U engine which did come stock in a 97 GP. With the aftermarket RIVA Head, and flame arrestors it looks like the makings of a stage II modified engine. You would also have to have the RIVA aftermarket CDI, a Solas "I" or perhaps "J" impeller (if ported), and rejetting for the complete job.

    That boat should be quick out of the hole.

    You should use the BR8HS.

  3. #3
    drewman's Avatar
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    I took off the cylinder head cover and screwed in a spark plug just to see how far it protruded, and it looks like the BR8HS is really short and only threads in about half way down. Then I put the BR8ES in and it came all the way down and the end of the thread was perfectly flush...anywho do you know where I might be able to get parts for the aftermarket RIVA head (like a head gasket)? Lastly, when I took off the cylinder head cover, cylinders 1 and 2 looked like they had about the same wear, they were black with just a slight rusting. However, cylinder 3 had no black and was just a light coat of rust like it wasn't being used? I also noticed that a cable going from the choke to the top carburetors 1 and 2 but the same spot on 3 was capped off, could this thing have possibly been running on only 2 cylinders?

  4. #4

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    The aftermarket head probably calls for an longer plug (3/4 inch instead of 1/2). If it ran on two cylinders, then it ran very poorly. Reguardless of wether the choke linkage is attached to two or three of the carbs, it would be wise to put a primer system into this model because they are notorious for being hard to start.

    Sounds like this engine has been neglected for a while, perhaps was running lean or water intursion in #3. Can you get the crank to turn? Pictures here would help a lot.

    Doesn't the RIVA head use an "O" ring system as a head gasket? The "O" ring will more than likely be orange or red. Of course your best source for that head is RIVA YAMAHA itself. www.rivayamaha.com

    Was it running well then sat up for a while, or did something happen then it sat up for a while? What is the history on this boat?

  5. #5
    drewman's Avatar
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    I haven't tried gettin the crank to turn, it does use the "O" ring I believe (it's red). The ski ran great and then it was having intermittent performance issues and that's he stopped using it and now it's been sitting in his backyard for 4 years. Attached are some photos of the engine and intake with the air filters removed:

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  6. #6

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    Yeah

    More than likely, the crank is gone. Maybe it was not 4 years ago, but it does not look good now. You can try to blow the cylinders out, then spray or add WD-40, kroil oil, anti seize into the cylinders and let it soak for a while then try to get the pistons to move. The real definitive way to find if the crank is locked is to seperate the pump from the engine and try to turn the crank by grabbing and turning the shaft.

    The two plastic lines in #1 & 2 are part of a primer system and is enough help in a cold start up.

    Sitting that long, it looks like at minimum you should do is pull the cylinder, hone, and rering the pistons... providing the pistons do not have any serious hours. You should also rebuild the carbs, as that may have been the root cause of the problem.

    The real issue is the crank, and from here, it does not look good. Quite honestly, from the looks of the red adaptors on the carbs, it looks like a part of the engine has been underwater and has partially corroded. We are talking full rebuild here. What does the corrosion on the head tell you? If it were mine, I would completely rebuild it just because.

    Hey you said you wanted a project. Looks like you got one!!!!

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