Carby Leaking carby problem

Discussion in '2-Stroke Engines' started by Irish John, Jul 9, 2009.

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  1. Irish John

    Irish John Guest

    I had a carby that leaked heaps out of the back. Probably where the air filter joins. I've replaced it with a new one but it still leaks a steady stream.
    The first carby was fithy with gubge but I cleaned it. The second one was clean and working last time I had it on a bike.
    Any idea what is causing the steady stream of fuel to leak out the back. Floats are OK so it's not that.

  2. kiwirider

    kiwirider New Member

    do you have an in line filter? Dirt can get under the fuel needle and seat and it will not shut off the fuel flow. The needle is inside the chamber where the float is. You should never have a dirty carb. Even a small amount of grit or rust from the tank will stick in the needle valve giving the problem you have.
  3. Irish John

    Irish John Guest

    yes I always have an inline filter. The carby is clean and if there is grit in the needle I can't see it when I take it all apart.
  4. Irish John

    Irish John Guest

    I've now tried 3 carburettors sooner or later fuel ends up flowing out of the airfilter and top of bowl like a river. Last carby was OK for a few minutes but it flooded and started flowing out in great quantities & motor stalled. Does anyoine have an easy fix for this. I have a $50 HT carby that's brand new but the other 3 are all OK so I don't think it's the carby itself. Could it be the fuel hose is too loose on the carby inlet? It's the Chinese kit hose I'm using.
  5. if the gas comes out of the airfilter part alot,then its a float problem.
    a drip or 2 out of airfilter after shuting off the bike is normal for these engines.
  6. Skyliner70cc

    Skyliner70cc Active Member

    Of my many builds, I've seen this happen about 4 times. Adjusting the float and cleaning the carb meticously never fixed the problem. I ended up buying a new carb each time and that seemed to fix the problems. There are two types of HT carbs, the NT and WH carbs. The WH carbs seem more prone this issue. I don't use WH carbs anymore regardless of whether they leak or not..their needle is to bluntly tapered and I don't like their carburetion as a result.
  7. Irish John

    Irish John Guest

    Cabinfever was right. It was the float needle & seat. I took it apart & cleaned it even though it looked clean and it works now. I also bent the lever thingy that the float pushes against so it became a little more sensitive and shut the fuel off better but that might cause problems later. It goes OK now. It's an all steel bike that is well suited to motorising with the 2-stroke engine although it was originally a battery powered bike. I don't know how why a battery bike would be so heavy because it is so heavy it is noticeably slower than any other bike I've done and I very much doubt it would have been a success under battery power.
    Thanks guys for your help.
    I usually use the newer carbs too with the different air filter but on this build it's the old cheap carby.
    4-strokes really are much simpler to keep running.