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bought a regular gravity feed petcock!

Discussion in 'XJ Modifications' started by RiceBiker, May 12, 2014.

  1. RiceBiker

    RiceBiker Member

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    Hey All,
    Has anyone had luck with a gravity feed (non-vacuum) type petcocks. I'm hesitant to rebuild the existing vacuum type petcock /because of "the incident". The incident being, '82 XJ650 wouldn't start after repeated goosing, compression start attempts, etc. Had a feeling something was horribly wrong when I noticed an empty gas tank after having put 2 gallons of gas in it. So, yeah all the gas was sucked in to the engine through the vacuum line via a faulty diaphram in the vacuum type petcock, I guess?!
    Drained the 3 gallons of oil/gas mixture (4qts oil + 2gallons gas), flushed with motor oil, drained again, then did another oil/filter change. Should be ok. Anyway, just wondering if anyone has had luck with the non-vacuum type petcocks. Do I need a higher volume petcock? Also, removed airbox, will use individual airfilters, leaving standard exhaust for now! But would like 4into1. A lot of time you have to re-jet for that. Bigger or smaller jets? Typically!
     
    RiceBiker, May 12, 2014
    #1
  2. Thrasher

    Thrasher Member

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    I have been using one for years, you will be fine.
     
    Thrasher, May 12, 2014
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  3. Bushy

    Bushy Active Member

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    Yes a non vacuum petcock is good, so simple and easy. You turn off the ignition you turn the tap off and vice versa. Block off the port on the intake manifold the vac line went to.

    The fuel probably wasn't sucked into the engine (unlikely) it was leaking float valves in the carbs that hadn't shut off (very common) You have to clean and check the carbs over.

    http://www.xjbikes.com/Forums/viewtopic/t=14692.html for starters
     
    Bushy, May 12, 2014
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  4. Ptrikk

    Ptrikk New Member

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    I need to upgrade to a gravity feed petcock as well, which one did you get? I'm not sure what will fit.
     
    Ptrikk, May 31, 2014
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  5. Xjrider92117

    Xjrider92117 Active Member

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    Why is it a upgrade ???
     
    Xjrider92117, May 31, 2014
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  6. RiceBiker

    RiceBiker Member

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    RiceBiker, May 31, 2014
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  7. RiceBiker

    RiceBiker Member

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    I don't know if it's an upgrade, its like, are you a PC or a MAC?!
     
    RiceBiker, Jun 1, 2014
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  8. RiceBiker

    RiceBiker Member

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    I don't know if it's an upgrade, its like, are you a PC or a MAC?!
     
    RiceBiker, Jun 1, 2014
    #8
  9. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    It's not an "upgrade" when you lessen functionality.

    Your problem of gas in the oil was almost certainly NOT caused by a petcock issue; but rather (as pointed out above) a stuck float or floats. Gas in the oil is a carb/float valve issue; all a faulty petcock does is "enable" it.
     
    bigfitz52, Jun 2, 2014
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