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Poor gas mileage

11 posts from 7 voices
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  1. Drick36

    2004 1100 classic , I was getting about 35 miles a gallon and now Im getting 29. I changed plugs, airfilter , fuel filter and it seems to have made it worse. I do a lot of freeway riding at 65-70 miles an hour and it is very hot here in southern Texas. Checked the plugs and they both have a nice brown tint to them. Bike has 36000 plus miles.

    Any suggestions as to what is wrong , has cobra slash cuts and Im not sure about jetting as I have not messed with that.
    Also it has been starting harder than usual and is very cold blooded.

  2. Rop123

    Sounds to be running VERY rich (obviously).....except that you said the plugs look normal and not fouled....hummm

  3. Destructo22

    Stuck floats maybe or maybe the floats need adjusting in the carbs, that will cause raw fuel to be dumped, which could cause hard starts, and obviously horrible mileage.

    Only real thing I can think of since it's been dropping on ya with no work being done. Might not be enough to make the plugs dark though since you mentioned the temperature and such. If this bike has stock jets and slip ons I wouldn't expect the plugs to really have much brown considering they are usually lean from the factory.

    I'm putting money on stuck floats or floats that need adjusting. You might be able to run some sea foam through it, but that will only help if there is some gunk in there keep the floats from stopping the fuel flow.

  4. 78ordon

    2004 1100 classic , I was getting about 35 miles...

    I would try some seafoam and see if that helps. I can't imagine you needing touch the floats.

  5. webster98

    i got one for ya, the fuel cut off relays, are they connected? if not (or if they are sticking) you can be flooding when not running with steady drip or small leak into the bikes intake so its completely unseen but when the bike is running everything is fine as you indicated it is with good color on your plugs.

    you should be getting around 45 mpg so sounds like a problem thats gradually getting worse until now its very noticable.

    run a few tanks of seafoam and maybe your just all gummed up but it may be time to pull the carbs and do a proper carb cleaning

  6. quicgmicg

    The bike is probably perfectly fine. Too many people jump to too many conclusions without asking all the necessary questions. There are a million variables that can cause a slight drop in fuel mileage and most of them have nothing to do with the bike set up.

    The most important question is this... how many tanks have been at 29 MPG? Has it been windy? You can drop 4 MPG just by being a little harder on the throttle or riding 5-10 MPH faster on the freeway than usual.

    Your plugs are giving you the best clue that you're pretty close to being on the money, but maybe just a slight bit rich. With alcohol enriched fuels, you should be just a little closer to a very light tan.

    I just ran 100 miles on the freeway this weekend and went through a tank of gas, which is close to your same gas mileage. I was just pushing it a bit harder than normal....

    If it's starting hard, it's just time to change the plugs.

    Also, without knowing your exact jetting set's going to be impossible to tell you exactly what you've got or exactly what direction to go. We don't even know if the intake is stock or not.

    What ever you not mess with the'll never get them right again without buying new ones. Do what 78ordon suggests and run a little fuel system cleaner through......and then try to find out what your set up is. Get us that info and we can get you going the right direction.

  7. Drick36

    Thanks Mick ,
    If you have ever been to south Texas you know how the wind blows here. And t has been blowing very hard here for a couple of months. I agree I think the bike is running fine, It is just a whole lot of varibles that are causing the drop.
    I am going for a 100 mile ride today , no passenger, hopefully little wind and I am going to hold the speed down to around 60 and see what I get.
    But it may be time for a carb tune-up and balance , Ive run seafoam thru it several times already.
    Ill let ya know what happens.

  8. Drick36

    I think you were right on Mick, I put on 75 miles and used 2.1 gallons , the wind was calm and no stop and go driving ,all freeway, speed was between 60 -65.

  9. quicgmicg

    Awesome! Glad to hear it. Synching the carbs is a good idea if you haven,t done it for a while.....

  10. webster98

    didnt notice you have a trike, my opinion was based on the average milage 2 wheel 650/1100's get

    and as mick said driving style and conditions have a lot to do with it, just a windshield on a bike can cost you 5 mpg at highway speeds

  11. bkman

    My normal commute to work takes me on one secondary road with a 55 MPH speed limit (for about three miles), but it is mostly stop-and-go slow-speed riding. I almost always get about 42 MPG. When I'm on the Interstate highway (going 70 - 80 MPH), my mileage isn't much better than that. In fact it sometimes is a bit worse (in high winds or if I'm pushing it more).

    However, if I ride between 60-65 MPH all day long, I've seen my gase mileage go as high as 48 MPG (or slightly higher). I also think you're probably okay. There is a sweet spot on these bikes (all bikes, I think - my buddy's Harley does the same thing).


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