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Thread: 91 or 98 fuel?

  1. #76
    Join Date
    7th December 2018 - 16:22
    Honda vt250 spada
    Ethanol attracts water
    Water doesn’t like lots of metals
    Lots of metals rust when they come in contact with water
    = why gull 98 isn’t ideal in lots of cars and bikes.

  2. #77
    Join Date
    15th February 2017 - 13:17
    BMW G310GS
    Ethanol can play havoc on some types of rubber seals as well. Hence best to avoid unless bike manufacturer says it's safe to use.

  3. #78
    Join Date
    12th February 2004 - 10:29
    bucket FZR/MB100
    Henderson, Waitakere
    I'm not sure why but my scooter runs better on Gull 98.

    As for flame speed, whatever the speed is in a still mixture it is too slow for anything but the slowest of really old engines. The squish causes high velocity gas to be ejected into the combustion chamber which causes turbulence and the fuel to be burnt in a short enough time to be useful. There are other methods of promoting the necessary turbulence. The useful feature of higher octane fuel is that it resists detonation of the yet to be burnt portions of fuel/air. This allows the use of higher combustion chamber pressures, either compression or boost, which then allows greater expansion of the burnt and heated gas and therefore more work extracted. Work extracted = torque. Detonation is violent and strips away the boundary layer of gas protecting the combustion chamber and piston from the searing temperature of the burning gas. If it happens often enough the alloy temperature is quickly raised to the point where it is weak and can be damaged by further detonation.

  4. #79
    Join Date
    8th January 2005 - 15:05
    Triumph Speed Triple
    New Plymouth
    Blog Entries
    Some Mobil stations were using ethanol too. To answer your original question 95 should be OK.
    There is a grey blur, and a green blur. I try to stay on the grey one. - Joey Dunlop

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