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Help Fuel PRI vs. Reserve

Discussion in 'Kawasaki 250cc In-line 4's' started by RyanZXR, Jun 16, 2020.

  1. RyanZXR

    RyanZXR Active Member Premium Member

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    Hi, Bike is running alright. Definitely needs a sync. However,
    I've noticed it dies shortly after starting with fuel cap set to PRI and when I flick it over to reserve there's no issue.
    What might be the issue? I prefer not having it on reserve 24/7 because it may or may not leak fuel.
     
    RyanZXR, Jun 16, 2020
    #1
  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    If a fuel tap has a prime option on it the tap is a vacuum operated tap, so will only let fuel through when the engine is running.
    The prime setting is incase you run out of fuel and refill the tank or if the bike has been sitting for a while and the fuel in the carby bowl's has dried up, when switched top prime it bypasses the vacuum shut off valve and let's fuel through

    It might be dying on prime as it can let too much fuel through if the needle's (needle's and seat's) aren't sealing properly)
     
    Last edited: Jun 16, 2020
    my67xr, Jun 16, 2020
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  3. GreyImport

    GreyImport Administrator Staff Member The Chief Contributing Member

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    Whats the go with having it in the 'ON' position .. ??
     
    GreyImport, Jun 16, 2020
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  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    On and Res are vacuum, with reserve having a pickup lower in the tank, prime is purely gravity feed and the only thing stopping with will be the needles and seats, and the o-rings on the seats in case of the ZXR. The seat o-rings are known to go bad, once they split the needle and set are incapable of controlling fuel supply.
     
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    Linkin, Jun 16, 2020
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  5. RyanZXR

    RyanZXR Active Member Premium Member

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    Thanks for the response, I see the difference now.

    Yeah it is strange, so if the needles and seat weren't sealed properly wouldn't it die if the tap was set to ON too?
     
    RyanZXR, Jun 17, 2020
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  6. RyanZXR

    RyanZXR Active Member Premium Member

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    Hey GI, I'll let you know this afternoon. I assume it'd be the same as RES.

    This all happened after I heard a loud 'pop' from underneath while I was riding if that helps.
     
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    RyanZXR, Jun 17, 2020
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  7. RyanZXR

    RyanZXR Active Member Premium Member

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    Ahh I see, yeah that's a possibility. My seats are brand new from motorcycle warehouse.au . The fact that the bike only does it when the tap is set to PRI confuses me. It doesn't seem to leak fuel when the tap is left open now anyways.
     
    RyanZXR, Jun 17, 2020
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  8. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    The seats and o-rings (Keyster) from Motorcycle Warehouse are a much better match than the OEM. The OEM part is too tight.
     
    maelstrom, Jun 17, 2020
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  9. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

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    I normally check the floats are actually floating as they can perish over time and have issues. But, I guess you would have noticed one was full of fuel when you had the carbs apart. The needle has a little spring inside that can also get caught and not work properly. Again, just giving you other options to investigate.
     
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    Frankster, Jun 18, 2020
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