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98 Ron fuel backfiring

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Ljiljan, Oct 25, 2009.

  1. I normally fill up with 95 ulp and the other day due to absent mindedness went for 98 pulp. I have noticed that coming off the throttle has occasionally caused the bike to backfire. I've noticed it three times now, although it may have occurred more when I am focused on other matters - usually the next corner.

    Is this backfiring normal and is the premium fuel the cause?

  2. Shouldnt be normal. Try checking your ignition, spark plugs, leads etc

    A weak spark may not be enough to ignite higher octane fuel reliably.
  3. Sounds like a lean burn causing the backfire coming down off the throttle.
    98 Ron fuel is supposedly denser so needs more spark by advancing the timing if it can be done manually. On an EFI bike the spark should be advanced on its own depending on the fuel map and whether it allows spark to advance.
    Also please tell us what bike you ride as it makes it harder to help.
  4. hyo gt250r, carbied. Dont plan to use 98 fuel again, 95 is 20c cheaper.
  5. Unless your manual states using 95 octane than 91 would be better. Or cheaper, I mean.
  6. It probably is the reason why it is backfiring. The 98 fuel is a lot denser and makes carbied bikes overfuel or run rich. My wifes VTR 1000 did the same thing for the few times we put 98 in it. Save money and use the 2000 from the quix.