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  1. #1

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    97 GP1200 Inconsistent Performance

    Last year I bought a 97 GP1200 needing an engine, so I got an SBT with 2 year warranty. It ran freaking awesome for 9 hours. Had to pull the engine and send it back for replacement. SBT says it was run lean. I followed the break-in procedure regarding fuel-oil mix ratio (unhooked the oil pump obviously) but didn't have the carbs rebuilt. Got the new motor and followed the break-in procedure to the very minute as described and with regard to plug change and fuel ratio and had the carbs rebuilt with the Mikuni parts. The ski runs awesome and strong with a higher pitched smooth sound and gets up to 60 mph rapidly and then all of a sudden, after an hour or so of riding, will change in sound and not have the same punch any more. It will get up to great speed gradually at WOT but doesn't do it rapidly like it does before the "change". I don't do any of the mechanical myself, so any ideas I would need to pass on to someone to check it for me. It also seems to smoke a great deal, especially at idle speed. I'm using non-ethanol fuel mixed 40:1 with Quicksilver oil, which is what my father has used in his 97 for years, and his runs flawlessly. Any ideas? Could it simply be spark plugs need changing for the performance? And what about the smoking?


  2. #2
    Yamaha artisan Cutlass's Avatar
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    First thing to do is check the engine's compression. Any automotive, marine, or powersports mechanic can do that test for you. Or maybe you know someone with a compression gauge that can do it? The results of that test will tell you if the engine is hurt internally or if not. If the compression test is ok, then you might have a carb or fuel problem.
    Post the results of the compression test here and we'll let you know what to do next.

  3. #3
    Yamaha artisan Cutlass's Avatar
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    About the smoking, 40:1 premix will smoke quite a bit at idle. that's normal.

  4. #4

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    I can actually do the compression test, so I'll do that and let u know. Thanks for the response. I'll get back with you

  5. #5

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    The front cylinder read 120, the middle about 114, and the rear about 105

  6. #6
    showmepro1200's Avatar
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    You very well could end up doing another engine swap. At least you got the warranty. As I'm sure you know from the manual DONT take the heads off or anything that would void your warranty.

  7. #7
    Yamaha artisan Cutlass's Avatar
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    That number 3 is too low. call sbt and let them know and see what they wanna do.

  8. #8
    Yea definitely needs a rebuild. you must figure out why its happening before ruining another motor. Who rebuilt the carbs for you? Need to make sure the jets are in good shape and they are set to default specs. Also make sure your water lines aren't clogged. Your pisser is pissing yes? And you're gapping the spark plugs correctly ?

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