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High Octane

Discussion in 'Bling and Appearance' at netrider.net.au started by Cronus, Aug 17, 2007.

  1. A simple question, would putting high octane fuel in your bike, say a 125 make much of a difference, i know u can fell it in a car so why not in a bike, and its a whole lot cheaper to fill a bike so there's no reason i couldnt afford an extra 10c.

  2. Depends on the bike. You wouldnt run some bikes on anything but high octane, but that is because they're designed / tuned for it.
  3. Yes, depends what type of bike. ex250s (zzr, gpx) don't run any better on high octane fuel, but cbrs and zxrs, etc do.

    That said, I run BP ultimate every once in a while for the cleaning stuff its supposed to help with carbs and FI.
  4. BP ultimate seems to run abit better than 91,95. BP ultimate the bike doesnt run as smooth when idling but aaccelerating is a tad better than 91 or 95.
  5. It generally depends on the compression ratio.

    Someone correct me if I'm wrong on this (I might be), but I've generally heard that anything less than 11:1 will be fine to use 91 Octane in, and won't really benefit from a higher octane fuel.

    Anything from 11:1 -> 13:1 you should be using at least 95 octane stuff in, and you might get some benefit from 98 octane if you're above 12:1. Anything above 13:1 and you should pretty much be using 98 octane always. Above 14:1 (very rare - and usually only after modifications), and you'd be wanting 100+ octane.

    The size of the cylinder bore has an impact though as well (so I've read). Larger bores will require a higher octane fuel at the same compression ratio as a smaller bore cylinder.

    All that generally means is that on a 250cc bike, with small bores, and typically quite low compression ratios (<12:1) 91 octane is fine, 95 octane may net you some marginal benefit, and 98 octane is just going to cost you more money.
  6. I started with 95 octane when I first got the VTR, but use 91/92 now. There's no noticeable difference (to me) in fuel economy or power, and I have been told the higher octane fuels can be not so good on carbouretted engines in the long term (fouling plugs etc) {clarification may be needed on that point}.

    Of course filling the tank of a 250, there's really not a whole lot of cost difference.
  7. That's the right concept Flux, but not the full story. The higher the compression ratio of a motor, the more likely it is to detonate, and the more it will benefit from a high octane fuel... not because it produces more power or anything like that, but because it resists ignition. The higher the octane, the higher the activation energy.

    This in itself doesnt give a power benefit, but the way in which motors are designed not to detonate and still run low octane fuel is through less than optimal fuel/air mixtures, retarding the spark etc etc. So it's more a case of a motor being able to be tuned to it's best when running on high octane and being de-tuned to run on low octane. The fuel doesnt make a difference except for stopping your motor going pop DEPENDING ON THE TUNE. High comp and low comp motors can both run low octane, depending on the tune.

    (Talking about octane only, additives and other differences in the fuel all complicate things).

    Someone will no doubt further add to this.

    Best bet I'd say though, is to go with your manufacturers recommendation. Don't waste your money if you've got a bike built to run low octane, dont risk your bike if it's built to run high octane.
  8. Thanks guys that does clear a lot up for, although i have done year 12 chemistry im not much of a mechanic, lol. so dont know all the ins and outs of engines and what makes 'em tick.

    Um dont believe this to be true because higher octane fuels need to are more pure and need to be processed and boiled more to get that level of octane in the fuel so if anything it should be cleaner then standard fuel, although that being said if it does not burn cause the engine cant ignite it, it wont do ur engine any good.
  9. Unfortunately some high octane fuels (notably Shell Optimax) are famous at every bike shop I know for having had too many chemicals added that bikes can't burn (thus the fouled plugs).

    Also the lovely volatiles (light hydrocarbons which make good burning) tend to evaporate really quickly out of optimax, which in a sealed car fuel injection system is impossible but in a bike carburettor say "bye bye" to easy starting and good running. That fuel can go bad OVERNIGHT in a bike, and some go bad in a week or two.

    The jury is still out trying to decide if Shell V-Power is any better.

    As for other brands, try it and see. And don't use less octane than your manufacturer recommends, just in case they are right. After all, they DO know a lot about your bike.
  10. My bike's manual doesn't actually state what minimum octane should be used, just says unleaded...so I figure that to mean regular's fine.
  11. My carburetted R1 loved Optimax and V-Power.
  12. Just got a new GSXR 750. They told me not to run anything less than 95 octane. Also not to use Shell optimax. Reason i didn't listen too.
    Didn't worry me, i have always put Caltex in my cars/bikes.
  13. Too much carbon build up from Optimax or Vpower as it is now. Mobil 8000 is the go for me, i use it in everything that i have to put fuel in.. :grin:
  14. High octane fuel should tripple your power and give you a longer penis.
  15. Hahahaha THAT'S why your putting 98 ron in there ibast! :grin:
  16.  Top
  17. Look at your manual. If it says, '91RON or higher' then chances are that you're wasting your money filling it with anything higher.

    If it says '98RON' then that is what it is recommended that you use.

    None of my (unleaded only) bikes benefited from running any form of 98 octane fuel in them, except for a ZZR1100 (first model). I used to run it on super (leaded fuel) til they phased it out. I then started witn regular ULP but it rattled and pinged under heavy load. But when I ran it on higher octane ULP while the pinging stopped I didn't notice any difference in performance or economy.

    My current bike, an injected Honda Blackbird runs just as nicely on ULP as it does on any flavor of PULP that you'd care to mention. The only difference is what it costs me, with PULP being dearer.

    I've seen mates put ULP in their bikes that are supoosed to run on higher octane fuel. They said that they couldn't pick any performance or economy degradation. Maybe over a long term the engine may suffer, but between fills it didn't seem to matter.

    Where it does matter are older vehicles that were designed to run on super, or high octane leaded petrol. I put a tank of ULP in one once and it ran like crap.
  18. But only if you sniff it

    It's call "new Nasal Technology"

    Haven't you heard the adverts??


    Not an actual fact. 4 out of 4 people know that sniffing petrol is not good for you, particularly if smoking at the time
  19. Good, accurate experience.

    If your bike is designed for ULP putting a higher octane fuel in the tank will not result in a noticeable or measurable performance increase. At the same time it shouldn't harm it, either.

    Consensus on Optimax some years back was that it ran "richer" and would possibly benefit from a slight jet reduction in certain circumstances. Still, in this weather it doesn't hurt to cool the combustion chamber a little more...


    Trevor G