5 miles to a gallon

Discussion in 'Motorized Bicycle General Discussion' started by cagle4cagle, Nov 6, 2011.

  1. cagle4cagle

    cagle4cagle New Member

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    i got got a motorized bike and the first couple of times i used it were on a full tank but when i stopped riding i noticed the tank was almost empty. Is there an issue with my carborator that is letting in to much gas? I observed the bike with the petcock closed and the gas does not leak so i do not have any leaks in the tank. Where is my gas going?
     
  2. Mozenrath

    Mozenrath New Member

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    5 miles to a gallon? HUH??? Wouldn't the gas have to be pouring out of the carb for that to happen?

    My only guess would be that somehow the engine is being really flooded, but I don't think it would run if that happened.
     
  3. leadfarmer

    leadfarmer New Member

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    Keep in mind the tank is 2 or 2.5 liters, so about 1/2 gallon of gas. Maybe that helps.
     
  4. CTripps

    CTripps Active Member

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    Yeah, but 5 miles is only around 8 km. I do that each way when working, and a tank can usually last me the week with some to spare (although I always top up mid-week) if I'm not taking too many side trips.

    Somethings definately not right with that.
     
  5. Mozenrath

    Mozenrath New Member

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    Most of the stock tanks come with rust on the inside, but cagle4cagle's fuel tank has a hole that goes into the Twilight Zone. laff
     
  6. CTripps

    CTripps Active Member

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    Must have. I know I ran through gas a little faster without a filter on, but never like that. It would have to be leaking badly somewhere.

    cagle4cagle, best I can suggest is put some clean dry cardboard or newspaper under the bike after a run (bring it up to temp then park it). The check on it regularily for marks. All I can think of is gas dripping steadily from somewhere in your carb while running. While travelling it'll disperse (mostly).
     
  7. Mozenrath

    Mozenrath New Member

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    Well, so I can actually contribute instead of yuk it up, here's something else I have to say.

    Are you really sure that fuel isn't leaking from your tank? Since I used rubber padding under my tank and since I had over-tightened the mounts, hairline cracks developed around the base of two of the studs. For a while I didn't even notice it was leaking, since overnight it would slowly drip. I was losing so much fuel! After epoxy fixes and poor solder work on my part, I just got a brand new tank from Pirate Cycles. I discovered that the best way to mount the tank is to use double-sided gorilla tape. That way vibration isn't transferred to the studs and I wouldn't have to over-tighten just to get the tank to stay in place.
     
  8. CTripps

    CTripps Active Member

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    I hadn't thought of that.. double sided tape would work pretty well. I'd probably still use the mounting hardware as well, but that reduces the risk of overtightening. On the two builds I've done so far I've had to add spacers below the tank on the bar for bike cabling to pass. I did have a cable stay on the frame cause me a pinhole a while back, and it took a while to become apparent and locate it because of the spacers wicking the fuel down the tube. A little gas tank putty and a slight shift back on the tube solved it.
     
  9. AslansMonkey

    AslansMonkey Member

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    Have you observed the bike while parked with the petcock OPEN? I had a bad float in the carb on one of mine that caused the gas to flow out of the carb and onto the ground. If you are very judicous about always turning the petcock off when not in motion you may not notice the loss of fuel this way as it's spread out in little drops along your path like bread crumbs.

    In my case either I or one of my son's (don't remember who rode it last) left the petcock open and I discovered a nice puddle under the bike.

    The fact that you have NO leak when the valve is closed points to a leak further down the system.

    Like another poster I also had a tank that leaked where the tank bolts attach to the tank. JB Weld solved that one.
     
  10. Al.Fisherman

    Al.Fisherman New Member

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    Tell your neighbor to quite stealing it.
     
  11. Mozenrath

    Mozenrath New Member

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    Regardless if the petcock is the problem or not, throw out the stock petcock. It's an embarassingly poor design and it actually limits the flow of the fuel. If you bested it open and looked inside, the holes that are controlled by the valve are HALF the size of the nozzle! The stock petcock doesn't really have hard on and off positions and it's prone to leaks.

    I made a petcock out of a barbed brass spout and a plastic fuel valve from Orchard Supply Hardware. The brass spout wasn't metric but it fits well enough into the stock tank that it stays in and doesn't leak at all. The plastic valve works really well, and I use E85, so I've found that it's extremely resistant to wear. And it has hard on and off positions!
     

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