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  1. #1

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    GP1200R carb questions - sticky throttle issue

    I have a 2000 GP1200R, about 77 hours on it now. The throttle has been sticking after the ski sits for a short time when hot. I have done a few searches, and it seems that the issue is a bushing on the carburetor that heats up, expands, and binds on the throttle shaft.

    The diagnosis is to heat the carbs up and see which one sticks. My question is, top or bottom? How hot do I need to get it?

    My other question is in regards to the "kit" supposedly available to prevent heat soak into the carbs. This thread mentions the following parts as something Yamaha offers to reduce heat soak into the carbs. Any experience, recomendations, etc.?

    68N-13556-00-00 GASKET, MANIFOLD
    68N-14271-00-00 INSULATOR
    90105-08041-00 BOLT, WASHER BASED

    Also, when I reassemble, should I just reuse the stock carb gasket, replace it, or reuse it and spray that permatex copper spray-a-gasket stuff on it that I used when I did the d-plate install? I'd rather not wait for a replacement if I don't have to.

    I have the carbs on the bench. First time I ever removed them. Not too tough, but I did wonder WTF yamaha was thinking in a few spots. They could definitely do a better job of designing these things for serviceability and longevity. I mean, zip ties on fuel lines? WTF? If you saw that on a regular boat you'd run the other way. Boating magazines bitch when things aren't double clamped with stainless hose clamps from the factory. Same deal on the oil lines. I'll have to rectify that when I reassemble, at least on the hoses I disconnected.

    I used the "cajundude" tech page to take it apart. Good stuff. It's a bit tougher with the exhaust on (not the "stinger," the other part that's harder to take off).

    My plan is to pull the throttle shaft on the offending carb(s), remove the bushing(s) if possible, if not, just insert a small file or rolled up sandpaper to increase the clearance slightly to allow for the heat expansion, grease it all up really good and put it back together. Anything i'm missing? I don't want to take this apart again.


  2. #2

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    Well, I heated them all up with a heat gun and they all bound up. So i pulled all the throttle plates and shafts. 3 of the screws unscrewed all the way, 2 broke (drilled out) and 1 stripped and had to be drilled out. Threads in one of the holes look a little rough, but serviceable, the rest are fine. Now I have to find some screws the same size and loctite the hell out of them.

    All of the shafts show signs of binding. I will be sanding the shafts and bushings and reassembling. hopefully tomorrow.

  3. #3
    Moderator OsideBill's Avatar
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    The screws in the throttle shaft are intentionly long then deformed so they won't back out. That is why they are so difficult to remove, you need to grind the end off first.

  4. #4
    There is no winter in Hawaii! tnerb's Avatar
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    Quote Originally Posted by OsideBill View Post
    The screws in the throttle shaft are intentionly long then deformed so they won't back out. That is why they are so difficult to remove, you need to grind the end off first.
    I wondered about that when I tried to get one of mine apart. I don't want to hijack this thread but that is great info. Mine would unscrew a few turns then bind up, I didn't want to go any further than that and strip the head.


  5. #5

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    I knew that but I didn't want to f with a grinder. The first one came right out, with a little bit of force.

    Has anyone reused the gaskets? I can't get them locally until Wednesday and I want to put this together today. They look like they're in good shape. Should I reuse them dry, reuse them with spray-a-gasket, reuse them with RTV, or wait until wednesday?

  6. #6
    Moderator OsideBill's Avatar
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    If the OEM gaskets are in good shape I reuse them and apply a little waterproof grease to them.

  7. #7

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    That sounds like a good idea, that ought to do the trick. they do look like they're in good shape.

  8. #8

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    Starting to reassemble now.

    If I had it to do over again, i'd grind the ends of the screws off. Drilling them out messed up some threads. However, threads on half of the hole still hold torque. I will be using copious amounts of loctite on all the screws. I thought about using a nut, but that would a - interrupt air flow and b - be one more thing to fall off and end up in a cylinder.

    If you do this, make sure you put the throttle blades on the exact same way they came off. The edges are beveled. Take a photo of the blads before you take them off, there is a mark on the blade that will help you in reassembly. I took a photo and it saved my butt.

    I am using new screws. Loctite 271 works fast. I had the throttle blade on wrong and had to disassemble, in less than a minute it was already hard to get the screws out.

  9. #9
    Moderator OsideBill's Avatar
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    Please keep in mind that if one of these screws comes lose it is going straight into your motor.

  10. #10

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    that's first and foremost in my mind. but i don't think it's all that likely, really.

    I am using the red loctite, which is generally way too strong for these screws. i'm also thinking about deforming the end somehow, like the factory does.

    I thought about using a nut, but a nut is more likely to come off and damage the motor than the screw coming out.

    There is really no load on those screws. if they will hold torque, there's enough thread, and there's really not much torque to hold. the loctite has to do it's job keeping the screws tight. the original screws didn't back out, and they didn't have loctite, and the mushroom feature on the end wouldn't keep the screw from turning, just falling out. And they were tight. So really, I should be good.

    If not, and the screw does make it into the motor, there's still only about a 60% chance it would cause a failure. It's small enough that it could just get pumped right out the exhaust.

    I'll work on it more tomorrow. For now, i'm taking my boat out.

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