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Km's to my tank

Discussion in 'Technical and Troubleshooting Torque' started by doonx, Mar 15, 2005.

  1. has now got me stuffed. My tank is 18lt capacity

    a few weeks ago, I got 350k's on tank full without going to reserve, the fill took 17lts, I thought this a bit weird, but anyway.

    Then on my way to Curry last Wednesday, I was at 310k and it konked out, went to reserve, no probs.

    Over the weekend I went to Dinner Plain. I filled at 240k's, then at 300k's and again at 200k's. No reserve required throughout this at all.

    Last night I went to coffee etc and then rode into work this morning, I konked out at Toorak Rd Exit with 230 on the trip metre. Again over to reserve and off I went. Obviously will fill up on way home this evening.

    Throughout that I have used normal unleaded, Premium Unleaded (98RON) and Mobil's Premium unleaded at 96RON. It was the 96 that got me the 300k's last time.

    Any ideas on what might explain this wild variation ?


     
  2. A variety of factors, the obvious one would be your right hand.
     
  3. Other factors would be sittnig in traffic versus cruising country roads and ambient temperatures. Don't forget that in warmer temperatures the bike runs slightly richer.
     
  4. excuse my ignorance, but if I'm sitting on 100-110kph for 2 hours, would that use more petrol than 200kms of city cycle riding (stop/start, high rev/low rev) ?
     
  5. Hey Pete,

    I've found a clear difference as far as mileage goes between the 98 ron fuels, premiums and regular unleaded. Some will tell you otherwise but I found an extra ~50km to a tank on the top shelf stuff. Be it Shell (yes, my bike runs just fine on Optimax) or Mobile, it get better mileage per tank than the standard premium and regular unleaded. I find I get really bad effects from Caltex these days, poor mileage plus the last time the bike would only run on 2-3 cylinders unless fully opended up. Try and stick to one type of fuel and see if you can get some consistent results. It's subjective but you may need to find a fuel the bike likes.
     
  6. Obviously not
    what would matter is HOW you get to 100-110 kmh slow and steady? or grabbing big gobs of throttle?
    Also a 250 can consume more fuel in percentage terms than a big bore at 100 because it revs higher.
    Like I said, it all depends on how you use that right hand and other factors.
    Simple logic really.
     
  7. Doonks,

    What Smee said plus.

    Higher Octane fuels have more energy. The result is you will get better milage.

    If you have a fuel injected bike with closed loop ignition you will gain a bit more on top of that also, because the ignition rums in a slightly more advanced state.
     
  8. Not really, but I'll spare you a chemistry lecture with the correction that 'higher octane fuels burn more effectively with respect to creating an expansion as opposed to an explosion effect'

    This ultimately means that less fuel is used to accomplish the same amount of work.
     
  9. Yep well said.
     
  10. Slash & Smee,

    My understanding is that to manufacture higher octane fuels in OZ they "crack" longer chain molecules. The result is they have a more complex molecular chain then a simply frction distilate.

    So with more bonds to break in oxidizing they do in fact have more chemical energy.
     
  11. When did I become a member of Guns N Roses? :?

    Without going into the chemistry of the whole fuel composition thing, the truth is a bit more counter intuitive.

    The simpler chemical structure of straight chain carbon compounds means that they oxidise more rapidly causing the shock wave to outrun the expansion wave (high explosive). Thermally this is more energetic but mechanically harder to harness (pinking).

    Higher R(esearch) O(ctane) N(umber) fuels have branched compounds, or RON boosters to enable a slower burn which means that the shock wave doesn't outrun the expansion wave to the same degree. Less energetic but mechanically easier to harness resulting in more effective power per volume of fuel burnt.
     
  12. Right on the money.
     
  13. This is not quite right. It is actually the difference in speed between the flame front and the 'shockwave'. If the shockwave out runs the flame front then you have an uncontrolled pressure rise and the associated heat rise caused by the reacting of the fuel in the combustion chamber. This is usually associated with the pinging sound you hear from engines as multiple flame fronts collide in the combustion chamber. Therefore to get higher octane fuels you want a faster burn or slower shockwave.

    There are actually more BTU's in octane enhancers like aromatics.
     
  14. :shock:


    muh traktor runs guud on petrooolium
     
  15. I'm used to cars that have been made for Premium ULP from the factory, so I've always understood it to be something like this:

    1. If you've got a new engine that's tuned for 91 RON (ULP), you won't see any benefit from using 95 RON or higher fuels
    2. If you've got an older or worn engine that's tuned for 91 RON, you'll see a benefit because your engine will be less susceptible to pinking
    3. If you've got a new engine that's tuned for 95 RON or higher, you'll see a detrement using ULP, as your engine will pink on high revs

    From what I remember, 95 RON and higher fuels don't actually give you any more power (as Shell et al would like you to beleive) but allow highly-tuned or worn engines to better realise their own power.

    I will also point out that if you're running a new and 95 or 98 tuned engine, or you're running a worn engine, pinking damages your engine. Most new cars are factory-tuned for 91-RON, but I'm not sure about motorbikes. I tend to run my Across on PULP because it's a POS with 80,000k on the clock.
     
  16. Pretty much what I said, just more detailed

    In terms of overall energy potential this is true but I was describing (trying to at any rate) the rate of burn as being more energetic not overall energy capacity.
     
  17. So for Donk's sanity, do we agree that he should get better efficency out of premium fuel?
     
  18. Sorry mate - got a bit carried away (as usual) :LOL:

    Premium is best! I get much better fuel economy and the engine runs more smoothly.

    (watch out for Shell Optimax though, only seems to really work for larger displacement engines - others may disagree)
     
  19. i only use premium in anythin,if yuh use standard u probably put sugar in yuh tank too, cause yuh think yuh bike has a sweet tooth
     
  20. yeah I failed chemistry. premium is better than regular coz it has more go juice bits in it, but not too much that your engine explodes.