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Doesn't Run on Reserve

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  • Doesn't Run on Reserve

    So after about five or six month of storage, I have been riding my bike back and forth to work. I started out the first of the year by running a bottle of seafoam through the tank, then remembering I needed to change the plugs when it wouldn't run right. So I changed the air filter for good measure, along with the oil and filter. Throughout this whole time I never put two and two together that the times it wouldn't run right--that I was blaming on bad plugs, etc. it was running on reserve. Finally I did a series of tests and have found that the bike just won't run on reserve. It runs perfectly on a full tank of gas but sputters and dies when switched to reserve. I can kind of mitigate it by leaving the choke on halfway when it is on reserve, but that just keeps it limping along and not really running right. I've probably gone through three tanks of gas (well, topping it off before it gets down to reserve) and today it started sputtering out when I was driving home on I-95. It was at 155 miles; usually I switch to reserve at 180 so I was cutting it close. Sure enough, I pulled over, topped it off and it ran perfect all the way home.

    Any ideas on what would be causing this...I could see the first ride of the season, if there were condensation in the tank or something but it has been three tankfuls bottle of Seafoam and one bottle of Lucas...and still a problem that is like clockwork. Turn the petcock to reserve and it takes off out of the driveway just fine but then sputters at the exact same distance from my house every time.

  • #2
    Junk that settles at the bottom of the tank gets sucked into the carbs when you use reserve. The reserve passage in the petcock might also be gummed up. My advice to you: refuel more often, you really shouldn't be using reserve with any kind of regularity.
    »Ross Wendell
    »1992 Katana 600, 1987 MR2 turbo, 2005 Corolla


    • #3
      Run the tank low again to need reserve, and set it to prime instead. If it runs fine, you simply need to clean your petcock (possible rebuild it). If it won't run well on either setting, flush and rinse your tank clean.

      93 750 Kat

      Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread

      "I've done this a thousand times before. What could possibly go wron.... Ooops!"


      • #4
        i hope you didnt poor the whole can of seafoam in at one time. one can treats 30+ gallons of gas, the kat tank is only 5

        the bottom of the petcock screen and top of the petcock body is prolly all scuzzed up as well as the internal reserve passage. pay attention to how the parts come out as it's possible to reassemble the petcock with the innerds upside down. be carefull with the vacuum diaphram also as they're fairly easily torn.
        99% of the questions asked here can be answered by a 2 minute search in the service manual. Get a service manual, USE IT.
        1990 Suzuki GSX750F Katana
        '53 Ford F250 pickumuptruck
        Lookin for a new Enduro project