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Fuel- 91, 95 or 98?

Discussion in 'General Motorcycling Discussion' started by bike_noob, Mar 16, 2010.

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  1. I have a GS500
    I was wondering which fuel would be the best for my bike?
    Is it worth paying extra for 98 octane premium?
    or should i just stick with regular unleaded 91 or just go in between with the 95?

    What bikes do people have and which fuel do you use? Have you been able to get more power or better milage from using 98 or 95 compared to the regular stuff(91)?
    Is there an negative side effects of using 98 or 95 in a bike like the gs500?
  2. Save your money and go with the regular. The only negative side effect to running 'better' fuel is a lighter wallet.
  3. True, on a GS500 using anything above 91 is going to be a waste.
  4. what about on a 06 zx-6r?
  5. This has to be one of the most asked questions on motorbike forums the world over. Use search.
  6. shady, carby or fuel injected?
    If its carby it would need to be tuned to the fuel. Fuel injected *might* self adjust... not sure on the bike exactly.

    I run 98 in mine because my other option from any of my local service stations is E10, and there is no way im running THAT! Ive had it tuned too.

    Its a common misconception that higher octane = more power from the fuel, thats incorrect, its just that it makes it harder to ignite the fuel (more compression required).
    Thats why some lower compression engines have issue with higher octane fuels.

    I seem to recall a thread a while back regarding Shell Optimax (98)?
    I think the actual fuel was too thick to use as some carby jets cant handle it, and a rejet would be required.
    Me, i have used BP Ultimate, Mobil 98 and have no trouble.
  7. My 08 CBR600RR recommends a minimum of 95. My 1990 GSF250 bandit only wanted 91.

    Check your owners manual, it will have all the details you need.
  8. +1
    The bike hasn't been overhauled in 20 years, its essentially the same as when it first came out.. anything more than 91 is an waste.
  9. I've a GS500F picked up on Xmas eve. Dealer told me to use 95 as it would be better but I didn't believe that was correct but I did use it for a few weeks.
    Then I checked manual which says to use 91 so I would assume Suzuki would know a little more about their engines than the sales bloke.
    To be honest, I can't really tell too much difference and if any, it seems to prefer the 91 which makes sense as higher octane fuel are harder to ignite.
    End of the day, the GS is an older (but proven) technology using carbies and not modern EFI systems on engines where some may have been tuned to run on high octane fuel.

    I think best bet is to go by manufacturers specs. After all, the built the darn things.

    Best part for me, no need to waste money on over priced fuel for a little bike that already has pretty good fuel economy..
  10. Word to the wise, salesmen are just that.
  11. Stick with what the manual says. I had a brief stint with 98 despite the manual suggesting 95 and suffered from fouling spark plugs, which on a fully faired bike is a frustrating arse of a job.
  12. Although the fact it is an old style 2-valve combustion chamber would mean hot spots etc, which leads to pinging, so older engines often respond better to higher octane fuel than newer engines.

    keep in mind that many bikes are designed for higher octane fuel, but have the ignition retarded to run on 91. so if they are borderline then you may notice some difference by running 95.

    I've had one suzuki that responded to 95 and another that didn't. The Triumph responds to one particular brand of 98 despite the fact the manual notes 95.

    So the absolute that "what the manual says only" is not such an absolute.

    So, try it and see, but joedelosa's post would suggest 91 is as good as it's going to get for the GS.
  13. Attached is Fuel Recommendation from manual stating 91 or higher.
    But as I said previously, from my experience it seems a waste of money and I've never experienced any pinking or knocking....
    I suppose the option is there to use a higher octane fuel so you could determine yourself if you feel you need to.
    It also sounds that Suzuki may suggest that in some parts of the world, advertised octane levels may not be accurate.
    I believe we'd can be fairly confident our companies are doing the right thing. (famous last words)

  14. Another +1
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