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  1. #1

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    Bad reed valves???

    After rebuilt the carbs, there is a lot of smokes from the exaust. This is the first time to own the 2 strokes ski, I don't know if is is normal?

    Also, I found out that the third cylinder won't run. There is sparks and everything.

    When I start the engine without the plugs in place, the fuel sprays out heavily from the 3rd cylinder.

    So I suspect the 3rd reed valve stuck open??

    I like to know for sure if it is the case, so I won't buying the wrong parts.

    Thanks.


  2. #2
    quadzilla's Avatar
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    ????????

    Testle..

    A little more information will go a long way to diagnosing this condition..

    1/. what ski are we talking about here..
    2/. how many hours on it..
    3/. did you check for spark with a plug in the end of the lead..?? (on the bad cylinder)
    4/. did you confirm its not a dead plug..?? (again on the bad cylinder)

    I would doubt its bad reeds...

    More likely a bad coil than anything else..??

    If there's fuel and spark.. you need to check the compression..!!!!

    Post up a little more info please..

    Gerry

  3. #3

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    Sorry, I forget to mention it is a 2001 XLT1200. It has 78 hours on it.

    The ski could start with either first or second cylinder alone, but not with the 3rd.

    I did interchange the plugs, as well as spark plug wire( eg. the first wire to the 3rd plug...) and got same result.

    I suspect because of too much gas to the cylinder???

  4. #4

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    The compression are identical on all three about 95psi (on my cheap Harbor Freight gauge)

    Even it runs on two cylinders (downgraded to an XLT800 lol.), it is able to clock about 59mph something on the eTrek GPS, but with a lot of unburn gas from the third cylinder

  5. #5
    nunnink23's Avatar
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    thats awfully low compression, unless the xlt motor is different i believe thats quite low. but on another note did it run before the carb rebuild? if yesthen theres your issue pull that carb off and re-trace your work

  6. #6

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    It ran much stronger after carbs rebuilding.

    After I bought it last September, I found out the power valve at cylinder 1 dropped. So wave-eaters installed.

    And the compression at the cylinder 1 is the same at the other two. So I guess I'm luck out.

    It could be I'm not doing the compression test right, but the ski start very easily, runs strong, accept for the smoke, which I found out from the 3rd cylinder.

  7. #7
    nunnink23's Avatar
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    thats true a comp test isnt the be all and end all, but i dont see how reeds could be that bad that they wouldnt allow the cylinder to even fire at all. id say pull them out, if they hang open visibly the engine is re-breathing every stroke which means it draws its intake charge, and then when the reeds should be shut and the powerstroke comes down while the other cylinder is on its intake stroke it will spray some of the fuel back out the bad reed into the carb which will be sucked back in next intake stroke. this typically only shows up at idle, backfiring upon sudden de-acelleration also could be bad reeds. i wouldnt jump to buying new ones till you inspect them. .001" per the yamaha manual is the maximum tollerance for them to hang open, which isnt visible so if there visibly open there shot.

  8. #8
    quadzilla's Avatar
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    ???

    OK then we're getting somewhere now... Time to get a "BETTER" compression tester.. But if the compression is even in all three holes that's promising.. Are you still on the oil injection pump or premix.. If premix then you will always get a fair amount of smoke at idle or low throttle positions.. If on the oil pump make sure the cable has NOT came lose or off..??!! NOW THEN:. If you are as you say getting high 50's performance (GPS verified..??) Then you are absolutely running on three cylinders..!! I would go as far as to say running very well also.. An XL1200 on two cylinders wouldn't even make it over 40mph and run like absolute Shit..!!! Gerry

  9. #9

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    I guess when running at hi rpm, the third cylinder can clear up gas, thus explain it is be able to fire up at hi rpm.

    At idle, it simly choked up with gas.

    I'm on pre-mix 40:1

  10. #10
    nunnink23's Avatar
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    Quote Originally Posted by testle View Post
    I guess when running at hi rpm, the third cylinder can clear up gas, thus explain it is be able to fire up at hi rpm.

    At idle, it simly choked up with gas.

    I'm on pre-mix 40:1
    most likely, if the reeds are really bad then it would idle like a bag of shit and run like one till you start revving it out for a few seconds or hammering on it when its just dumping fuel. i would honestly check the reeds before buying anything. 2 strokes are finicky and reeds are one of those things that can be a real headache, just make sure a .001" feeler guage doesnt go under the petals, dont force it in, just as long as it doesnt slip in easy.

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