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Premium Fuel in an Across?

Discussion in 'General Motorcycling Discussion' started by johnmoz, Aug 29, 2012.

  1. I've been using premium (Caltex 98) in the Across, but I saw a comment somewhere that I shouldn't 'because of the additives'. The only thing the book says is 91 minimum.

    Urban myth, or fact??

  2. Not a myth. 98 octane fuels often have a higher density and will cause the bike to run rich (not to mention the fact that you're pissing money away).

    Stick with 91.
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  3. Put simply, your bike isn't tuned for higher octane (read harder to compress) fuel.

    Stick with 91 unless you want fouled plugs! :)
  4. don't do it
  5. wow just read other thread about 98 fuel.. ive been running 98 in my carby bike since new almost 3yrs now maybe the odd 95 if 98 was not avail... i thought the 98 would be better for my bike and get me more KS to a tank... i think i wil stick to 95 from now on... i dont trust 91 at all... thanks guys...
  6. I ran 98 for a week (4 tanks) in my Across. It fouled the plugs and it didn't run very well. Thought it was fuel related, so put new plugs in, ran 98 again for 2 tanks and it was the same. Pulled the plugs back out, gave them a clean, ran 91 and have had no problems since. Stick to 91, the Across was not designed or tuned for 98. I did run 95 once...didn't make much difference...so back to 91.
  7. In simple terms, the octain rating is proportional to the fuels resistance to self ignight under presure. The amount of engergy avaliable int eh fuel decresses as the octain rating increases.

    You should always use the lowest octain rating that does not allow the engine to detonate (fuel ignights before the spark plug ignights it).

    High performance engines use high octain fuel because they have a high compression ratio and therefore would detonate if they used a lower rated fuel.

    So basicaly, the performance of the engine will decrease with increased octain rating
  8. With the 91, just make sure its not the E10/ethanol crap - not good for the rubber seals/bits in the bikes in the long run.

    With the 98 I also found the bike to be a bit more sluggish, could be due to the smaller engine size (250cc)
  9. Use the pure 91. I used 98 Caltex for a while on my Hornet then read about 91, switched to that and it started up much easier when cold, ran easier and didn't have a 'stumble/hesitation' when it was being revved up

    Just avoid the E10 91 - that shit is not for bikes
  10. Wow, I'd call that unanimous, 91 it is from now on.

    Thanks folks

  11. Indeed, if the engine isn't tuned for it don't use it, as others have said your just pissing away money.

    I use 95 in mine (the manual says 91) just because the extra detergents in the fuel keep carbon deposits low.
  12. I never really bothered about what octane fuel I put in my bike, generally 91 but only because it's cheaper.

    My bike has always had a habit of icing the carbies in winter, it's just one of those things. Anyway a mate of mine suggested I use 95 or 98, because it's denser it might take longer to ice the carby. Well I tried it, and it still ices, but not as bad or as often.
  13. I used anything and everything in the old across and it ran like shit regardless.

    My advice? run it on e85 so that it rusts to hell from the inside so you can buy a new bike sooner.