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  1. #1

    How Should my Plugs look at how to adjust the mixture

    Ok just bought a 1997 GP1200 with 140hr on it and i am trying to do some maintenance on it as i run a little rough and has some idle problems. I checked compression on all 3 cylinder and it reads 110 on all 3. I change the plugs to NGK gapless per what i read on another forum. I adjusted the low speed screws on all 3 cylinders back to stock and have check adjusted and lubed just about every thing i could. I took it out for the first time the other night and brought it back and took out all 3 plugs and adjusted the idle screw up some as it was idling low. Here is my delema, when i looked at the plugs starting with the cylinder closest to the oil pump this is how they look. Starting with cylinder #1 the plug looks very black and oily, cylinder #2 not normal color but a little more on the black side, #3 looks the normal the brownish color. I will also add this is still Oil injected as i was going to wait until the end of the season to go to pre mix. I need help, as i am pretty sure this is not correct. I have also notice the idle is abnormally rough and i would assume this might be coming from the plugs. Any idea's on how to fix this and how do i adjust to lean or rich on my mix.


  2. #2
    Yamaha artisan Cutlass's Avatar
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    how rough is the idle? they do shake bit at idle. How does it run otherwise?

  3. #3
    It sounds rougher and appears to run rougher than i have seen on some posts on you tube. I just want to make sure all 3 cylinders are running evenly. Shouldn't they all burn the same?

  4. #4
    Yamaha artisan Cutlass's Avatar
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    Might be time to clean and rebuild the carbs.

  5. #5
    Ok now its a new issue. So i took my ski out when i wrote this post and now 4 days later the ski won't start. I pulled the plugs checked compression again still fine. Checked for spark and it appears that i don't have spark, but i have not put a meter on it yet. The other thing that happened when i was flushing the ski out after my run last sunday i did not see that my young son had turned the fuel switch off and i am now assuming that was causing my motor to race. Do you have to reprime the fuel system and or how do i figure out if i am getting fuel to the carbs? I need help i just bought this and have only had it out one time before this happened.

  6. #6
    Yamaha artisan Cutlass's Avatar
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    These things can be a pig to start sometimes. That's why a lot of people put primers (like the ones on snowmobiles) on them so they can pump some fuel in the engine for easier starting.
    My suggestion to you, maybe try squirting a little bit of fuel down each carb and see if it'll fire up. If you can get it to run a little bit like that, usually the fuel system will "reprime" itself and it'll run on its own.
    If it won't run with a bit of gas, then maybe you really don't have spark. There are several possible culprits like the ignition coil, the ign wire and end cap, the CDI, the stator (need to test the charge coil and pulse coil), the STOP switch, and temp sensor, but most commonly on this engine is the stator.

  7. #7
    Resident Coffee Addict Oshawapilot's Avatar
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    x2 on the difficult to start. I started mine for the first time this year and the *only* way to get it to fire after sitting was to pour some gas in the carbs - it fired up immediately and was then happy. A primer bulb is in my near future.

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