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1980 XJ650g Starting/idle problems

Discussion in 'XJ Technical Chat' started by arcplusone, Dec 3, 2009.

  1. arcplusone

    arcplusone New Member

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    Hi all, first post here...

    I received a 1980 XJ650G with 7000 miles on it that sat for a year and wasn't run.

    A coworker is currently trying to fix it up for me, and I figured I would help by trying to do some research.

    Any advice will be passed on to him and his response will be posted here.

    Any advice? Thanks a bunch!
     
    arcplusone, Dec 3, 2009
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  2. nsosh5

    nsosh5 Member

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    One: Float height make sure it is correct, It sounds like the needle isn't seating and is still letting gas in after they are full. Therefore flooding the crankcase.
    Two: The "vent" valve is their because the carbs run a vacuum to bring gas from the petcock to the carbs. When engine is OFF there should not be gas coming from the ON or Reserve postions. If it is you will need a petcock rebuild kit and that could be a possibility of flooding the engine. When the engine is off only the PRI postition allows gas to come though. It is used to fill the bowls after you put the carbs on. Check the petcock then get back with me.
    Three:Idle is more of a throttle position and should be at about 1050rpm's.

    If I missed anything let me know. And if none of this doesn't help let me know. Good Luck.
     
    nsosh5, Dec 3, 2009
    #2
  3. SLKid

    SLKid Active Member

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    +1 Nsosh
    There are 3 positions on our stock petcocks. PRI ON and RES
    Pri is the only one that should let fuel flow freely.
    A good way to check if your float needles arent seating correctly would be to open the air filter and turn the petcock to PRI. And if gas goes into the airfilter box then you have to adjust/replace the floats and/or needles.
    There is a 'Oil Breather Hose' in out airboxes and the gas enters the crankcase though that hose.
    I found that out the hard way as well. My mistake was that I let the Petcock on pri for three days. :(... My very first motorcycle.. I made a BUNCH of noob mistake with this bad girl.
    This site is awesome. We'll be happy to help you out in anyway we can.
    Dont forget to talk with our resident parts supplier Chacal.
    HE"S THE MAN
    btw
    -Chris
     
    SLKid, Dec 3, 2009
    #3
  4. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The carbs on these bikes are complex instruments that are very susceptible to getting gummed up from sitting and being clogged by rust particles from the fuel tank.

    This isn't something that's going to be fixed by halfway "tinkering" it's got to be done right or it won't get fixed, you'll just keep fighting with it.

    The carbs are going to have to come off; get broken down and carefully cleaned and any worn or deteriorated parts replaced. Then the float levels will need to be correctly adjusted using fuel and a clear metering tube.
    The carbs will then need to be bench sync'ed; and once back on the bike, vacuum synced and their idle mixtures adjusted.

    Then and only then will the bike run properly. Short cut the process and it won't work. You'll need a shop manual.
     
    bigfitz52, Dec 3, 2009
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