Home Forums Motorcycle Tech Talk R80GS high fuel consumption

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  • Dave Ross
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    Post count: 2310

    I am pleased to report that the R80GS did rather well at the CCA, pulling up hill like a tractor. I was never in fear of losing traction and could stop and start at the steepest hills. I am sure the knobbly tyres had a lot to do with it, but most of it was due to the characteristics of the bike.The trip was only marred by the high fuel consumption of my bike. At one stage it was 8 litres per 100km, in other words, more than twice as much as an F650 uses. Partially this may have been due to the way I used the gear box, I may have shifted to 5th gear too soon, causing it to run out of puff. I am not used to riding it for long distances and it is certainly no 1150. However, user error aside, I still think the consumption is unacceptable. What are the most likely causes? I will check the air filter today, just in case it has inhaled too much dust. Could the carbs need an overhaul? If so, who should I get to do this? Could I do it myself?I am looking forward to your thoughts.Alex

    Stuart Burns
    Participant
    Post count: 71

    Alex, the airheads are notoriously thirsty! Be worth checking that the float needles are seating ok, quite common for them to leak, maybe they're ok at rest, but are leaking on the move? Check for smell of petrol when you come to a halt.

    Mark
    Participant
    Post count: 103

    hi Alex sounds normal to me they are a hungry bike especially if u ride it hard over a 100kmh and if your trying to compare it to the newer bikes  don”t

    Dave Ross
    Moderator
    Post count: 2310

    Alex, the airheads are notoriously thirsty! Be worth checking that the float needles are seating ok, quite common for them to leak, maybe they're ok at rest, but are leaking on the move? Check for smell of petrol when you come to a halt.

    I'll check that Tony, now that you've mentioned it, there may have been a wiff of petrol. I've had the right bowl leaking once, well pissing out petrol. Perhaps that is related. The air filter appears to be pretty filthy, that can't be good either.

    Dave Ross
    Moderator
    Post count: 2310

    hi Alex sounds normal to me they are a hungry bike especially if u ride it hard over a 100kmh and if your trying to compare it to the newer bikes  don"t

    I've been told they use around 5-6 litres per 100km. On the way down I was using about 7l/100km. I suppose the knobblies and the luggage couldn't have been too good for it either.If that consumption can't be reduced I'll have to trailer the bike down in 2010. Three bikes on a trailer and three guys sharing the gas must be more economical. However, we'd miss out on a lot of fun on the way down.

    honeybear.2399
    Participant
    Post count: 232

    If that consumption can't be reduced I'll have to trailer the bike down in 2010. Three bikes on a trailer and three guys sharing the gas must be more economical. However, we'd miss out on a lot of fun on the way down.Fun='s $'s  PHil

    dave.valma
    Participant
    Post count: 86

    My R90 outfit that admitedly has a large frontal area gives me 10ks per litre when I am enjoying myself and 12 1/2 kpl when I cruise between 90 and 100 ks. Economical they ain't,

    Dave Ross
    Moderator
    Post count: 2310

    Well, I now have another problem. The battery seems to be dead, even though the charger is telling me otherwise. After a night on the charger not even the neutral light wanted to come on. I could find no obvious faults with the wiring. Unfortunately, I no even less about the electronics than I do about carbs.I wish one of you airhead gurus lived closer to my area, so you could come and have a look. I may have to trailer it to Experience to get them to check it out.

    Dave Ross
    Moderator
    Post count: 2310

    Ha, I've figured it out :-). Because the bike wouldn't run I thought I'd grease the the throttle cam and gear. I nearly damaged the part until I figure out that I had to remove the brake reservoir as well. Now it's got all the grease in the world. I was still disappointed with the action so I had a closer look at the cable. Sure enough one side had frayed. Looks like I need a new one at some stage.Next I looked at the starting issue again. The charger kept telling me that the battery was fine. Well, maybe it was, so I checked all the cables again. Nothing wrong with those. Then I remembered the issue I had with the 1150. Lets just clean those terminals and see what happens, I thought.Pressed the starter and the thing cranked- like a really cranky thing. But why doesn't it start? Crank some more then, with choke on and every thing. Hmm, perhaps I'd flooded it?. Took the bowl off to check, but it was dry as a bone. Ah, I did arrive home on the smell of an oily rag, perhaps I should put it on reserve? God, I am an idiot. But hey, you live an learn. The R80 is alive again! 😀 😀Alex

    dave.valma
    Participant
    Post count: 86

    Alex it sounds like you are on well the way to being your own airhead mechanic, start with the simple things first and you will always find a solution.

    Brian
    Participant
    Post count: 63

    Alex When the time comes to rebuild the carbs, let me know. If I can do it, you surely can. You can also get  rebuild kit from BING in the states here at  http://www.bingcarburetor.com/Cheers. Jim And yes I am slowly writing a report on our trip!!!

    dave.valma
    Participant
    Post count: 86

    Alex, Check out the prices of the parts of Bing international before buying, from my experience with doing a pair of pre 1970 bing carbs they were by far the dearest. As I suggested to someone else you may be surprised at the NZ carb part prices through experience BMW, check with Neil, they used to be very reasonable, might have changed now with the Aussie link up though.If not Motobins take a lot of beating, online catalogue etc. they are all small parts so freight shouldn't be an issue.Steve.

    Dave Ross
    Moderator
    Post count: 2310

    Thanks for that. Ross has suggested I also get a new needle and needle jets. Well, what he really said was to spring for a pair of Mikunis, and to stop complaining about the price of things.The bike has 110000km on the clock. I don't know what the expected life span of Bings are and when it becomes uneconomical to service them. I am not a stickler for originality, so the Mikunis could be an option, they are supposed to be a bit of a performance upgrade as well.Unfortunately the throttle bodies on my 1150 could also do with a bit of attention. The shaft has developed a little bit of play, which makes a ringing sound. As I understand this is not urgent at this stage, but a shaft replacement should be done before the bushes wear out.Still, it's heaps cheaper than having to watch a new bike depreciate. Instead, I get to appreciate my old bikes  😀

    Stuart Burns
    Participant
    Post count: 71

    If I recall correctly, when I had a throttle body on my 1100S replaced under warranty cos it developed excessive play, the cost of the new body was only 70 pounds (less than $200) I was very surprised!

    Dave Ross
    Moderator
    Post count: 2310

    If I recall correctly, when I had a throttle body on my 1100S replaced under warranty cos it developed excessive play, the cost of the new body was only 70 pounds (less than $200) I was very surprised!

    That's good to know. Perhaps I'll practice deferred maintenance in this case.

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