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  1. #1
    cconigliaro's Avatar
    Join Date
    Oct 2011
    Boca Raton, FL

    Mixed new gas with old gas STX-R, Ultra 150

    Today I finished my project STX-R and before I started it I cyphened out all the old gas in the tank, or so I thought I did. I added my oil for the 50:1 mix and headed to the gas station to put 14 gallons of gas in. I start pumping gas and it's full at 8 gallons. Shit, there is 6 gallons of 2 year old gas in my tank. I started it up and it seemed to run fine, rev fine, but idle was a little rough. I'm looking for suggestions. Should I throw it all out or use an octane booster? Will an octane booster affect my carbs or cause any damage? Not sure if it's fine to run like this and don't want to cause detonation. I'm also not sure if the old/new gas mix will hurt the carbs either. Please let me know your thoughts.

  2. #2
    wotxxxsd's Avatar
    Join Date
    May 2012
    I've always been told to pump n dump the old fuel.
    If you clog up fuel going into a cylinder it can cause that piston/ cylinder to burn up..
    I was told this about a 1300gpr that I bought with 1 yr old fuel.
    Better to be safe than sorry....

    You do want octane booster / fuel treatment in your mix.

  3. #3
    wakejunkie's Avatar
    Join Date
    Jan 2012
    SML, VA and RDU
    U should be ok just keep an eye on the fuel filter. If it starts to suck inward from the walls then dump the tank n replace filter/refil new gas

  4. #4
    RLACEMAN's Avatar
    Join Date
    Aug 2011
    Random Lake WI
    Did the old gas have ethanol in it, this can be a huge problem if it did, did you put premix oil in the tank enough for a full tank? if so you will be very heavy on oil. I get rid of my old premix by dumping a little in with the tractor or an old car from the 60's we have. If you leave it in, dump a can of Seafoam in with it.

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