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  1. #1

    Just Bought 1997 Gp1200 Please Help!

    So I finnally got around to buying my second ski after the first one was a nightmare. (Threw a rod in under 2 hours of ride time)

    So yesterday I bought a 1997 GP1200 with a fresh top end, carb rebuild, gas lines, oil lines, primer kit, ect. Owner claimed to have only 20 hours on it since rebuild. He showed reciepts for all of the parts and said that he had the bottom end flushed by the machine shop who did the honing even though it didnt need it due to there were no shaving or anything of sort. It was flushed while still together nonetheless still did seem to do everything the way it should be done.

    After a long in depth inspection of the ski inculding but not limited to a compression check (125 psi on all cylinders with snap on gauge) I took it for a test ride and it ran perfect. Started right up, plenty of power with no problems except it did bog for barely a split second at one point but then never sumbled again. Also, had a little bit of water spraying in the motor area but seemed to be coming from the flush hose that goes into the motor as it rubbed on the driveshaft a little. In my eyes no big deal Ill throw a new hose on it.

    Then the fun begins. On the way home I decided to throw it back in the water to look at the leak a little closer to make sure it was the hose so I could order one and as soon as i put it in the water and hit the gas it started bogging extreamly bad and ended up stalling. Started it back up and same thing happened. Ended up messing with the primer a little and it helped me keep it running and restart i enough to get it back to the trailer. Still starts up with ease on trailer and revs fine. Compression still strong. Plugs were dry brown tipped when I put it back on the trailer. After running on trailer plugs come out black and wet.

    So I have a couple questions.

    1. It was cold out (32 Degrees). Could that of been a problem? Ran fine before so I dont see how that could be but who knows.

    2. Kind of points to carbs? Starts up so easy though kind of makes me question it along with I can see the fresh gaskets.

    3. Could the water leak be something more severe like creaked exhaust that would cause this problem?
    Reason I wasnt too concrened before was it wasnt a ton of water just kind of a dripple.

    4. Do the spark plugs sound normal?

    5. he was running some premix along with the oil injection which kind of leads me to think it could be running to rich but at the same time doesnt explain the bone dry brownish plugs.

    Any advice would be greatly appreciated! Thank you all!


  2. #2
    jeffg426690's Avatar
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    A water leak and hose rubbing on driveshaft is bad ju-ju, fix that before doing anything else.

    Does sound fuel related. How long was the ski sitting before the test ride? How old is the gas? Go through fuel delivery, fuel vent check valve (if stuck closed, can starve fuel delivery to carbs), lines, selector valve if still on ski, fuel filter.

    Temp does matter in air/fuel ratio but not for your scenario of a/b comparison in same conditions, same day. Cold air is thinner and will be more lean generally speaking but shouldn't be a factor here. I wouldn't run it hard in that temp for very long, that's probably pretty far outside the temp range the carbs are dialed into from oem spec. I'd be a little concerned about a lean sieze in air that cold.

    Running on trailer really doesn't tell you anything, there is no load on the motor. You can't tune or diag a fuel issue at all on the trailer. My plugs are usually wet and a bit black after flushing on the hose on trailer.

    Why premix along w oil injection? Zero need for that and in my opinion alters the air fuel ratio. If you have more oil, you have less fuel is my train of thought on that. Check the oil lines and replace them if the haven't been replaced, upgrade the clamps at the carbs (which is where oil injection failures occur)

  3. #3
    steve45's Avatar
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    If the hose was leaking, and it was spraying water on the driveshaft/drive coupling, that would create a cloud of mist in the engine compartment. That may account for the wet plugs and poor running.

    As Jeff said, fix that first, then try it again.

  4. #4
    Check the primer pump and fittings. My old ski had similar and it was drawing a tiny amount of air from here. Ended up removing it on Yamaha guys asvice. They can damage the fuel pump.

  5. #5
    Yamaha artisan Cutlass's Avatar
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    Donít run your ski at 32*F and wonder why it runs funny. That seems silly.
    Another red flag is that the bottom end of the engine was not disassembled and resealed. On a ski that old, thatís asking for airleak trouble.
    Carb rebuild means nothing unless it was done with genuine Mikuni kits. Other kits last about 30 minutes (exaggeration, but slightly serious) before their quality fails.

  6. #6
    dewzee1200's Avatar
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    Quote Originally Posted by QBhoy View Post
    Check the primer pump and fittings. My old ski had similar and it was drawing a tiny amount of air from here. Ended up removing it on Yamaha guys asvice. They can damage the fuel pump.
    All my 2cycle Yamaha skis have Hot Products fuel primer pumps. How can these damage the fuel pump? Please advise I have triple carb rack on the bench now for rebuild after a 2 year lay up. Any info will be appreciated

  7. #7
    Hey guys thanks for all the advice! Ended up fixing the hose but probably won't have the chance to put it in water for at least a wekk as Temps are under 30 here. In the mean time I'm probably going to bypass the fuel selector, switch to oil injection, put new plugs in, and then give it a go.

    How nervous should I really be about the bottom end gaskets? The last thing I feel like doing is tearing the whole motor down just to replace the case gaskets. Lol he also showed me the carb rebuild and I belive it was the mikuni kits if I remember correctly.


    Last but not least I checked the lines on the primer kit and it seemed to be starting to melt as they were too close to the cylinder. It wasn't melted enough to leak but definley something I'm gonna address.

    Once again appreciate you all taking your time to respond!

  8. #8
    Yamaha artisan Cutlass's Avatar
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    Itís not so much that the fuel pump gets damaged from a primer pump, itís more of a problem to damage the engine. A primer pump installed on the fuel supply line to the carbs could introduce air in the fuel system and cause the engine to run lean. A lean running engine will not last long.
    So the recommendation is to install the primer in the fuel return line. The problem there is that the return line will probably be empty of fuel after sitting for a week. When there is not fuel in the return line, you canít easily pump prime the engine. To combat that, the recommendation is to install a longer return line that loops down low into the ski so that a bunch of fuel gets trapped in the bottom of that return line for priming purposes.
    Iíve found that sometimes the primer wont have enough fuel in the line to prime, but if I crank the engine for about 10 seconds, the fuel pumps begin to bring fuel up from the tank and into the return line and then I can prime the engine with the primer pump.

  9. #9
    Yamaha artisan Cutlass's Avatar
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    Quote Originally Posted by yinzer View Post
    Hey guys thanks for all the advice! Ended up fixing the hose but probably won't have the chance to put it in water for at least a wekk as Temps are under 30 here. In the mean time I'm probably going to bypass the fuel selector, switch to oil injection, put new plugs in, and then give it a go.

    How nervous should I really be about the bottom end gaskets? The last thing I feel like doing is tearing the whole motor down just to replace the case gaskets. Lol he also showed me the carb rebuild and I belive it was the mikuni kits if I remember correctly.


    Last but not least I checked the lines on the primer kit and it seemed to be starting to melt as they were too close to the cylinder. It wasn't melted enough to leak but definley something I'm gonna address.

    Once again appreciate you all taking your time to respond!
    The ski is 22 years old. The rubber crank seals and paper case gaskets are possibly old a brittle and leaking. If you can do a pressure test on the crankcase and it passes then you are good to go. Otherwise youíll have to find the leak and reseal it.

  10. #10
    I was looking around on the forum for a diy pressure test builder for the 65u motor but just kind of go brief Details. Do you happen to know of a good write up off the top of your head? If not I'm sure when I get home and use my computer it'll probably be easier to search through. No big deal. Thanks!

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