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Extremely poor fuel economy

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by bugeater, Oct 14, 2006.

  1. I filled up my Blackbird yesterday and got an estimated 8.9 km/l :shock: This just doesn't seem right.

    I mostly commute a relatively short distance: 5 - 10 km each way (depending which day it is). The 5km ride is mostly traffic free. The 10 km ride is usually in traffic, but still not too bad. I'm just skimming the CBD of Melbourne (Flemington Road, Elizabeth St, Victoria Avenue(?)).

    I just can't understand that sort of fuel consumption. I have noticed a smell of petrol when parking it at home. Could it be running too rich? I do have a Power Commander on its way. The chain also needs tensioning, which I'll do this weekend (got a torque wrench yesterday). Could that affect it? Should I use more gears? - I'm mostly in first and second.

    This tank was almost purely commuting, whereas my previous tanks involved a fair bit of freeway or higher speed riding and I was getting about 13-14 km/l.

    It's also still pretty new with only about 2,500 km on the clock.

    Any ideas appreciated :(


     
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  2. Wow. I'm sensing deja vu. Oh wait. I am. I saw this exact same post elsewhere. Something to do with Australian Blackbirds....

    Don't fret, mate. My 'bird ain't much better. But it probably needs a tuneup and service. It's got over 30k km on it now.
     
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  3. Have u accuratly estimated the km/L ???
    ...otherwise i can suggest....
    • Stop riding up steep hills :eek:
    • Decrease number of burnouts :wink:
    • Decrease number of wheelies :twisted:
    • Plug hole in tank :roll:
    • Stop going to dodgey servo who has slow pumps :)

    ahh i hope you get it sorted out :grin:

    EDIT - yay i got the BBC code to create a list :grin:
     
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  4. If you're only doing REAL short trips, you'd be better off with a scooter; using a 'bird for commuting is a gross under-utilisation of its capabilities....

    But if you're doing a lot of first and second gear stuff, any vehicle will use more fuel under that sort of regime.

    Plus the engine is still new and tight.

    But apart from that, IS there a known problem, Martin?
     
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  6. that sounds real high. my commodore gets 11.2. ill stick with 750's if thats correct.

    i just wonder since you said you smelt petrol at home if you had a small leak. might be worth leaving something like paper under the bike to check overnight. might be tiny but if you get crap in the carbies, you may have a seal not sealing?

    Then again those l/kms have been verified
     
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  7. This consumption is high for a Blackbird. Some people claim consumption figures in the high teens. I got half that.

    If anyone has experienced anything like this for any bike, it would be nice to know if they discovered the cause. If it is my riding style, then I can try to change that. The reason I only use the first two gears is because they are so long. Realistically I could ride to work and back without having to change from first. I could do the speed limit on the freeway in first.

    As to underutilization of the Blackbird - my bike has to do everything - commute, tour, blast around on the weekend. And lets face it, it's illegal to use it to its full capacity :)

    Oh and the consumption has not been verified, but it should be reasonably close. I always fill the tank to the same level and reset the trip meter. Naturally there will be a small level of variation, but you tend to notice when you get 60-70 km less out of a tank than you have been getting. I've been a card carrying scientist for many years - measuring things is what I do :p
     
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  8. You will use 2-3 times the regular amount of petrol when the engine
    is cold and the choke or fuel-injection-cold-settings are on. That is
    natural for all cars and bikes. If you read a 'save petrol' brochure from
    the government or any reliable source, they suggest if you have two
    cars and you need a short trip, drive the warm engine even if
    it is a v8.

    The smell of petrol is the unburned extra petrol coming out
    of the exhausts and is natural for a cold engine.

    The extra petrol is needed for two reasons: to mix better with the cold
    air (which needs more petrol to burn properly than warm air does)
    and to replace petrol vapour which condenses on the cold cylinder walls.

    Your engine will produce condensation/steam while it is cold and that can
    mix with exhaust gases in the muffler to create an acid water. Normally
    that blows away and evaporates when the engine warms up, but on
    a short trip like this the engine never gets to warm up so you could
    be collecting acid water in the exhausts. It is the most common cause of
    severely rusted and rotted exhausts within a few years of purchase.
    To prevent this, every couple of days warm up your engine properly
    on a decent ride.
     
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  9. Don't take this the wrong way, but do you weigh 200kgs? :p
     
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  10. The Blackbird warming up is unlikely to be a problem. I warm it up for a minute or two before I leave and the bird gets to operating temperature very quick. Besides most trips are 15 - 30 minutes, and it gets to operating temp within a couple of minutes. It may be a factor, but I'd be surprised if it fully explained the problem.
    I also doubt water is collecting in my exhausts. If you felt how hot they get you would understand (melting your shoes onto them when brushing against them is a problem) :shock:

    As to my weight - no I don't weigh 200 kgs :)
    I'm a light weight at only 75kg (and that's fat for me :) )

    I'm wondering if a dodgy batch of petrol could have an effect :facepalm: Another possibility is the O2 sensor playing around with the mixing I guess....

    I guess I just have to keep tracking the situation and see how things go.

    I'm sure it is a combination of a lot of factors, but I've just never seen such a dramatic change in fuel consumption before. My previous bikes and cars would vary by a few km/l, but not by this much.

    Marty
     
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  11. At a rough guess, I'd have to say that it's your riding style, Bug.

    Running around in 1st or 2nd gear is almost guaranteed that you'll slurp the stuff faster.

    Just because it can rev out to say, 110 km/h in 1st, it doesn't mean that this is the most efficient way of running the bike.

    How fast do you think you ride at, maximum, along your commuting route? The bike can easily handle trundling along in 4th or 5th at speeds around 60-80 km/h. It's idling over at those speeds. It wil struggle to accelerate, of course, but if it's a constant speed, then you should be fine in those gears.

    That should help produce the best economy.

    I take it that the 'bird is your first large capacity bike? If so, then you'll find that its capacity and higher torque than those 250s you have listed in your profile have the ability to do a lot more work with a lot fewer revs.

    I might suggest too, that now you have the big bike, enroll in a HART course.

    Good luck.
     
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  12. And there's the reason!!!

    Low speed, stop-start and cold engines uses more fuel than high speed freeway run.

    Go do a tank on the freeway and you'll find it has magically repaired it self.
     
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  13. I would guess that it is part of the problem, but not all. A 50% increase in fuel consumption on what is already poor for the model is unusual. In every other vehicle I driven/riden, you expect at most about 15% change between pure freeway and pure commuter traffic. Maybe the bird is unusual, but 50% is strange.
     
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  14. Agreed. I'd suggest, as I did earlier, that it's your riding style. By leaving it stuck in 1st or 2nd, you're almost guaranteed to get crap economy. Snick it up an extra coupla gears and see how you go. The engine has the torque to handle it.
     
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  15. That's the plan. I'll see how it goes :)
     
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