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gas mileage?

Discussion in 'XJ Technical Chat' started by Crash Fistfite, Aug 10, 2015.

  1. XJ550H

    XJ550H Well-Known Member Premium Member

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    could you expand on the alt. thing ? I notice a differance in the way my bike runs when i am running the valley floor compared to the mountain range
     
  2. MattiThundrrr

    MattiThundrrr Not a guru

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    That is the way it is with carbs. They are set up for an average altitude. If you look at a re-jetting guide, they always list different jets based on altitude as well as mods. It has to do with less dense air the higher you go.
     
  3. MarkDS

    MarkDS Member

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    From my reading the higher the octane, the lower the energy content of gasoline at 'standard' pressures. Gains are only achieved from high octane if you have an engine with enough compression to warrant it. More losses from ethanol as it has a lower energy content than gasoline. I run strictly Shell 91 octane in my XJ650J as it seems to be the only (or close to the only) pump around Ontario that has 0% ethanol.

    Maybe it was all in my head, but I put some 'off-brand' premium in my bike the other day because I was on a long trip with no Shell on the way and it seemed not to run right until I refilled with Shell.

    I do not work for Shell or affiliates (I work in the solar industry as it happens).
     
  4. Yorshire

    Yorshire New Member

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    Hi I realise this is an old topic, though still relevant, I'm seriously thinking of buying a 1981 XJ750 Trike (though the frame looks very much like a 1984 XJ900). The current owner recons he gets about 25 - 30 miles to the gallon and thats an imperial gallon (I'm English) so about 20 -25 to the US gallon. Is this normal or pretty rubbish? The lowest octane available here is 95. Although its a trike its pretty much a std bike with a back axle (from an old british Reliant) and a four into one exhaust from a GSX 750 I think (its got Suzuki stamped on it).
    To go slightly off piste, I'm supprised how many ratings of petrol you have in the US, I hired a car when my son and I came over to the IMSA meeting at Road America last year and the choice was quite baffling

    Cheers
     
  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    25 to 30 for Imp gallon is kind of low.
    how much does the machine weight?

    what are you running for tire size?

    you should check the frame vin and motor vin to ID them both properly
    this link explains how in detail or you can just use the link.
    TECH TOPIC: Model ID and VIN's

    do you regicter your bikes from motor vin or frame vin?
     
  6. Dave in Ireland

    Dave in Ireland Well-Known Member

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    Extra drag from the car diff and extra wheel, also them being wider rubber. It's still pretty rubbish, though. A friend triked an XS1100 and still managed high 30s mpg, more if he tried harder.
    I can average 29mpg from the GS if I wring its neck around the back roads, but it's not kind to the old brute. The worst mpg ever was about 20mpg over a weekend spent just horsing around locally giving it handfuls every yard. That same engine could do 60mpg at a steady 60mph.
     

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