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What kinda fuel for a Madass?

Discussion in 'Maintenance and Servicing' started by Mark Gibbons, Aug 7, 2013.

  1. Bought my Sachs Madass for some idiotic reason and I'm stuck with it for a couple months until I save up some funds for a real bike, meanwhile last night I saw some debates on other forums for specific bikes about which fuel is best.

    The manual for the bike I own [2010 Sachs MadAss 125] said 91 which is exactly what I've been using for the last month, but a few owners swear by premium.

    I'll be honest and say I know nothing about fuel, or close to it. Can using premium hurt the bike? Is it healthy? With so many different opinions, and not really being able to find out the facts, It'd be nice to know.
  2. it's a small capacity gutless bike that isn't state of the art....stick to 91....your only hurting your wallet otherwise - that's the common sense speaking no real education behind it so feel free to wait for others input.

  3. It's $3 for a tank- money isn't an issue with this thing. And yeah. But in saying that, since it is gutless, anything extra that'll help it along is always a bonus
  4. High octane fuel will kill your engine and you will not get more power - they're not made for it. It's a 125 - don't expect to go over 90km/h mate. Low octane burns slower so you'll get more distance on a tank. Using 91 saw me get 125+ km on 5l and 95-98 saw me get about 100 km.
  5. thankyou.
  6. you're welcome.
    • Like Like x 1
  7. If you are only keeping it for a couple of months, run it on what you like. 91 in a low tune engine will do it no harm (the ethanol content might do damage over a longer period).

    The higher octane stuff burns cleaner and gives you more bang for your buck (in higher tuned engines) but the extra performance comes at a high HP/$ rate that you won't notice anyway e.g. the difference between 12hp and 12.5 hp.
  8. Dunno what kind of 91 you get in your neck of the woods, but I don't see much else here apart from E10, so, I suggest that you try a tank full of 95, without Ethanol, see how far you get for your dollar, and figure it out for yourself, if it makes sense to use 95 or 91.

    Neither will do harm to your machine, but you may well find that you go further on 95 than 91, if the 91 is actually E10.
  9. Not generally true. All other things being equal, there should be no difference between high and low octane fuel so long as it meets the engine's minimum requirements. The octane rating is a measure of the fuel's ability to resist knocking (exploding instead of burning) under high pressure. It doesn't measure how quickly a fuel burns or how much energy it contains or anything like that. Ethanol, for example, contains less energy than petrol but is more resistant to knocking so has a higher octane rating (so expect to get worse fuel consumption if you use E10 fuels).

    All other things aren't necessarily equal, though. For example, when I looked into this a few years ago, Australian law required that fuel marketed as "premium" contain a lower concentration of various impurities (meeting the Euro fuel standards) while the rules for regular unleaded were more relaxed. Higher octane fuels also tend to have different additives, which are supposed to clean the engine, etc; I have no idea how effective these are.

    I almost always put in the lowest octane rating fuel that the vehicle is designed to run on and have never had any problems, and haven't noticed any difference between using low and high octane fuel in a low-performance vehicle.

    Interesting ... the only E10 that I've seen here in Melbourne (at United servos) is 95 octane, though not described as "premium". It's usually a few cents per litre cheaper than regular 91 unleaded.
  10. Madasses are awesome
  11. #12 CrazyCam, Aug 7, 2013
    Last edited: Aug 7, 2013
    Ah! I did wonder if the fuels were the same here, in NSW and there, in Vic.

    When they first started adding Ethanol to petrol, here in Sydney area, the E10, 10% Ethanol, was rated as 93 octane, which is just about what you'd expect, if you knew the octane rating of Ethanol, then, with the passage of time, E10 became 91 octane, which, I assume, reflects the refineries' cost cutting in the recepie for their "standard" 91.

    So, in Sydney, my Street Triple, which will run perfectly happily on 91 octane fuel, and equally happily, drink E10, I now feed it 95 octane because I get more kilometres to the litre without the Ethanol..... again, perfectly logical if you know the latent energy of Ethanol compared to "real" petrol.

    Oh, just remembered, higher octane fuel tends to have a slower burn that lower octane fuel, not the other way round.

    When I had my Striple on the dyno, the dyno operator offered to squeeze more top end power by altering the spark timing, but this was conditional on me using 95 or 98 octane fuel.

    I declined the offer, since there are still servos in the bush that may not have too much choice of octane.