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  1. #1

    00 Yamaha Gp1200r Cylinder 3 HOT

    Hello,

    I am in some need of help with my 2000 Yamaha GP1200R. I ran it for the first time this year and everything was going well for the first five minutes, reaching speeds of 60mph. After 5 minutes it bogged down on me and i couldn't accelerate past 1-2mph. I pulled it up to the beach and cylinder 3 spark plug was extremely hot in comparison to the other two. All three spark plugs are brand new. When i pulled it out of the water and ran it, i easily was able to get up to 6000rpm. Anyone have any ideas on what the problems maybe? I have the service manual but not sure where to start, can anyone point me in the right direction, please?

    Thanks
    Pierre


  2. #2
    XLTNoob
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    Please post pics of the plugs.

  3. #3
    All hail the Chief! fullboogie's Avatar
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    Probably means you are running extremely lean on that cylinder, or an oil line has popped off. In any case it sounds like you seized the #3 piston.

  4. #4

    Suggestions??

    Quote Originally Posted by fullboogie View Post
    Probably means you are running extremely lean on that cylinder, or an oil line has popped off. In any case it sounds like you seized the #3 piston.
    Yesterday, I started digging deeper into the machine but ran it one more time. After running I pulled the spark plugs out and cylinder 3 was hot again and there was some white smoke out of it. Sorry didn't have a camera to take pics although spark plug 3 insulator was starting to get yellowish brown. My fuel selector switch is very difficult to turn, but I don't think this can cause one cylinder to get hot. Why do some people say that it is common for cylinder 3 to get hotter than the rest or is the first to get hot. Anways after removing the exhaust I noticed some looks to be fresh oil under the carbs closest to cylinder 3 but all the oil lines were connected and showed no signs o leaks. Where could this oil have come from or is it possible it could have been there for a while? I really don't want to seize the engine, anyone got ideas for my next move?

  5. #5

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    Do not ride it anymore until you come up with a definitive plan to fix the problem. Two strokes are unforgiving when they are not set up right, and it could cost you serious $$$$ for that 2 minute test ride.

    First check cylinder compression to make sure you have not already damaged #3. Use a good compression tester looking for compression to be within 10psig of each other. For example 123, 128, 124.

    If they are good, the simplest fix that may work is to remove the anti tamper cap on your high speed adjuster and open it up.

    Worst case scenarios include things like
    1. Cleaning your whole fuel delivery system and ridding it of debri.
    2. Checking to see it your fuel tank is maintaining pressure. You need a bit of pressure to drive the fuel from the tank to the carbs, and with out it, you could run lean. This is very true with a low tank level. A simple way to test is to see if your gas cap pops off when you remove it. You will hear it "depressure".
    3. You may have to clean your carbs and possibly rejet to cover the lean spots that these carbs historicaly have.

  6. #6
    Hello Salty,

    I did a compresstion check on my GP1200r and cylinder 3 had 110psi, 2 120 psi and 3 125 psi so I think the cylinders are still ok. I replaced the fuel switch and fuel filter but this did not fix the problem. I took it to the local shop and had them do a check. They think the problem may be with the accelerator pump or need to rebuild the carbs, do you think this is the problem? If it is the accelerator pump, do you think disabling it will fix the problem rather than rebuilding the carbs?

    I just do not understand how it could go from running great to bogging down and not being able to get the machines past 2mph and 2500rpm in the water. On the land it revs to 7000+rpm. I feel like there may be debris in the gas tank or fuel lines so I was thinking abut disconnecting the fuel line inlet and outlet and blowing it out with an airline. What are your thoughts?

  7. #7
    It's not the accelerator pump but rebuilding the carbs is a good idea as they may be gunked up and making it run lean. I would pull the head and get a look at cyl 3 as well, 110 compression ain't all that great.

  8. #8

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    I don't think that you will like what i suggest. I'm thinking worst case scenario with 110 psig. It should be obvious to you that something is very wrong, and at this point it will not get better with minor adjustments. The good news is that you may have caught it at an early stage. Truthfully, we really do not know what the problem is at this point. We are guessing and will no know until we take a look inside.

    Pull the head and inspect for head, ring and piston damage. Also check for markings on the cylinder wall.

    Rejet the carbs per OsideBill's specs and do some reading on carburetor issues with the GPR.

    There are so many ideas about why the #3 cylinders are lost on the 66V engines. Some may be the symptoms, whereas others may be the real problem.

    You will read things like the pin at the ring gap falls out, the end of the ring rotates around to the exhaust port, breaks the ring and destroys stuff. Crank twist. The power valve drops causing major damage Not enough fuel is getting to #3 because of fuel line location, the fuel selector switch is a restriction and does not allow enough fuel to the carbs, not enough back pressure on the fuel return line, not enough fuel pressure to the carbs..... the list goes on and on.

    What ever the problem is, one of the things that reduces the chance of it happening again is to rejet the carbs and go premix.

    I would guess at this point that your problem is fuel related. If you rejet and go premix, you will reduce fuel and oil related problems to a minimum from here on out. At least historicaly this has worked for the 66v engine.

  9. #9
    All hail the Chief! fullboogie's Avatar
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    There are two reasons why #3 usually gets torn up first: stock cooling setup makes it run hot, and #3 is at the end of the crank and gets funky ignition timing due to crank twist. It's usually not fuel problems because the fuel line enters the #3 carb.

    As as been stated in this post, you are probably seizing the #3 piston and are on the verge of catastrophic failure. You gotta figure out why its running so hot before you kill it.

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