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Trying to get a old XJ running again

Discussion in 'XJ Technical Chat' started by jon kwarsick, Jul 17, 2020.

  1. jon kwarsick

    jon kwarsick New Member

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    Lately I have been trying to fix up a old 83 XJ900. I bought it a long time ago for 300 dollars cause a friend chopped it up and didnt know what to do with it after he did. I drove it a few times for a few years but never got around to fixing it up. About 5 years ago I took it apart cause it needed fork seals brakes and tons of other small things. Time got away from me and this year i am finally trying to put it back together. Frusteration after frusteration I am pretty sure I have the bike mostly back together still need to put the master cylinder back on and bleed the front breaks and wire in lights. The thing I am really looking for help about is when I installed a battery and tried to start it it wouldn't start. Now i have worked on way more cars then bikes so this is all really new to me. with the magic of a little starter fluid I did get the bike to start for a split second this tells me my problem is most likely fuel. A car has a fuel pump from what I understand a bike is gravity fed. now I took off the lower fuel line and the line that runs to the boot of one of the carbs which I am assuming is some kind of vac line. the tank was parked the whole time with a little bit of fuel in it so i figured maybe it got gumed up in there. I removed the tank drained as much as I could. Took my little 3 gallon air tank and blew some air into the lines. The vac line wouldnt let air flow through it but the line I think is the fuel line let air right through but never the whole time I was messing with it did any fuel come out of the pitcock. what am I missing?

    Little info about the bike. Most of the cosmetics were chopped up but it seems most of the workings of the bike were kept mostly stock. K & N air filters and a few repairs looks to be made like that fuel line is some kinda see through plastic green line where the vac is a good black rubber line. The tank it self has seemed to have major repair work done to it. Its looks like JB weld all over the bottom and looks like a ceramic liner is in the tank so i am imagining it had a bad leak. The Pitcock seems to be non functional always on most likely due to the ceramic liner I just mentioned.

    A little info about me. I have ridden many different bikes on and off dirt but never done much repairing only maintaining here and there. Worked on many of my personal cars and trucks but am no mechanic.

    Any help anyone could offer would be great.
     
  2. tabaka45

    tabaka45 Well-Known Member

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    If it is the stock petcock it should have three positions: Prime, Run, Reserve. Run and Reserve only work when the bike is running and the vacuum line is connected. The vacuum opens the petcock when the bike is running. When not running, and therefore no vacuum, the petcock closes which prevents any fuel entering the carbs in case a float needle valve fails. Prime is used to allow fuel to flow without vacuum and is used primarily after the carbs have been worked on or you run out of gas completely. If you have no fuel flow when the petcock is set to Prime, then either the petcock is gummed up or the strainer inside the tank is totally gummed up. If it sat for a long time either or both could be the problem.
     
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  3. jon kwarsick

    jon kwarsick New Member

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    As I said the Pitcock only really has 1 setting cause before it ran no matter where you moved the pitcock. I am assuming the piece inside the pitcock is no longer connected to spin the guts. So I need to create a vacuum to see if fuel will flow from it now?
     
  4. Rusty81

    Rusty81 Member

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    Doesn’t take much vacuum to open it. I used some Tubing and just by sucking on it like a straw I could feel the diaphragm open and close.
    Taking a petcock apart to replace the guts isn’t too difficult and at least you’ll know what’s going on. It’s probably just sealed from varnish or tank lining breakdown
     
  5. tabaka45

    tabaka45 Well-Known Member

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    We are assuming that you have the stock petcock.
     
  6. jon kwarsick

    jon kwarsick New Member

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    I have played with it more using air, I got air to go all the way through the gas line to the lid of the tank so that isnt 100% blocked. I sucked on the vac line and got about 2 drops of fuel out. So at this point my guess is the vacuum thing inside the pitcock is no longer opening. I took it apart and it was a bit stuck to remove but after reinstalling it didnt function any better. My move now is to try to find either a new pitcock or new guts I guess.
     
  7. Rusty81

    Rusty81 Member

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    hogfiddles and Timbox like this.

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