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1/2 full or 1/2 empty?

Discussion in 'General Motorcycling Discussion' started by Black Betty, Aug 4, 2005.

  1. I've always felt that my car handle better on a full tank of gas - figured it was something to do with more weight in the back, etc (I'm no mechanical engineer!).
    So why is it that I feel my bike handles better with less (below 1/2) petrol in the tank? Is it to do with the weight being higher up making the bike harder to lean?

  2. Interesting this. I think you've summed it up best when you say that you "feel" it handles better. There will be a slight improvement in weight distribution as petrol is burned off, but it would be hard to detect I think.

    I guess the bigger the tank, the bigger that effect would be. It would also impact on power-to-weight ratio as well.

    I will check next time I'm riding and see what it feels like, I've never actually considered that.
  3. I just assumed my bike liked the "coffee dregs" better than a full tank. :p
  4. I actually thnk you'd be better off with a completely full tank or a nearly empty one as in between this the fuel is sloshing around in the tank...does that make any sense at all??
  5. Maybe that helps me lean into the corners better - the swash of the petrol :?:
    Not sure if I can handle the stress of running out of petrol going out with an empty tank, but I REALLY notice it with a full tank. The bikes over double my weight - is that what you mean by power to weight ratio thingy?
  6. :wink: Sure it is.......I believe you.....it's the others you have to convince :roll:
  7. Didn't know they handed out licenses to 95 year olds? :p
  8. With old age comes gullibility.
  9. Tricky one this, more weight in the tank would create greater inertia making it harder to move the tank sideways ie lean the bike. However having the weight higher up should also create a stonger force making the bike lean further for a given amount of input force. The question is which one wins out?
  10. fuel=weight
    less fuel=less weight
    less fuel high up=lower centre of gravity

    Actually I've long noticed that cars and bikes always go faster when they're CLEAN!?!? :D
  11. Yes, the lighter the rider the more power is available to propel the bike. Also the less inertia is required to move the bike from side to side while cornering (I think it's inertia...anyway) That's why my VFR is struggling at the moment.
    That's also why you'll see that most racers are small and light, it all gives them an advantage on the track.
  12. WRONG - my car's VERY dirty and I can still managed to loose 6 points.
    My Bike on the other hand gets cleaned before and after rides and to date (touch wood) no fines :!:
  13. Depends how far you lean!
  14. Good point.
  15. OK - so maybe its a psycological thing - full tank = heavier bike = hesitant on the leaning, whilst less gas = lighter tank/bike = happier to lean further
  16. It's not psychological. A full tank of fuel is a lot of weight to shift around (14L = 14kg).
    Particularly if your fuel is held within the 'tank' that sits in front of you (on many modern bikes this is usually just a cover for the airbox, the petrol is held lower down, nearer to the bikes centre of gravity for exactly the reasons you are stating).

    Buells have for a long time used a similar argument for placing their exhaust cans low down. As exhausts are heavy items to move around, they argue that keeping this weight low down so it moves a shorter distance, makes the bike much easier to turn.
  17. Incidentally, the Japs are now starting to do the same thing with their cans.
    Kawasaki is the first to offer a bike with the can positioned underneath the engine. Could this be the next craze? Quite likely...
  18. 14L petrol = 10.5kg? :p
  19. Smart arse :)

    (Never was very good at chemistry. Anything beyond making little explosions & I got bored very quickly.)