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Thread: carb help!!

  1. #1

    carb help!!

    Hi guys. My friend recently bought a used Yamaha GP1200r from 2000 new bild engine.When we tested it for the first time a qouple of days ago we discoveredthat 1 of the cylinders were dead at low speed.when we gave it a litle more throtle it took off.So we suspected the low speed jet in the carb were clogged ..but after dissasembling the carbs we discovered that the low speed needle srews were tightened max on all the three carbs??? cant be a stock setting ?Some one must have been there before us and tightened them...We have been searching the web for houres.

    Help plece

  2. #2
    TexasZ's Avatar
    Join Date
    May 2012
    Near San Antonio, Texas
    If they are like that now, you are fixing to have much bigger problems. Instead of trying to do minor adjustments I would suggest doing something else...your call though...

    A really good thing to do, as well as a much 'needed' thing to do with a GPR that old is to rebuild/upgrade the carbs, the updated version per Oside Bill's recipe. As stated, it will really wake that ski up. Take a look at the link below for the carb rebuild articles. After that look at all the many articles written pertaining to the GPR in the "Sticky" section at the top of the page.
    If you're not comfortable with re-building the carbs yourself, PM WFO (Rich) here on the forum and get him to do them.
    Either way, "it's really important to rebuild them"...and "soon".
    You can rebuild the carbs now or wait and replace a piston or pistons as well as a cylinder or cylinders after one or more of the carbs leans out.
    Just take a look at the many many many stories of that happening and the cause.
    Also notice that in most of those cases, they were going to "ride first and do the carbs later" as well as the other needed maintenance items.
    Change the fuel filter also and take a look at the "sticky article" about the fuel pickup flapper warping and restricting fuel flow.

    Not trying to scare ya, just trying to save ya a whole lot of money as well as a whole lot of grief, regret and aggravation..

  3. #3

    Join Date
    Jun 2011
    you damn right!

  4. #4
    Can it be waek spark?

  5. #5

    Join Date
    Jun 2011
    you still need to go thru the carbs and rebuild and good i mean a good cleaning. texas hit it right on the head, that balencing mod for the carbs is a must for a carb gpr. i would hate to see a new engine get toast because of dirty out of tune carbs. if you don't already have a service manual for the machine you need to get one, it will take you thru the steps of testing the electrical components and disassembly.

  6. #6
    A got spark at all cylinder and a have the carb rebuilt but the air screwes is still tighten, spark plug att the 2 cylinder is litel more wet whit gas

    Henrik from sweden

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