Carby if its not one place leakin its another

Discussion in '2-Stroke Engines' started by determined, Apr 21, 2014.

  1. determined

    determined Member

    I first fixed the leak at the bottom of the tank with plumbers tape and a homemade gasket then discovered the stock fuel hose was just not tight enough so I replaced with new fuel hose and everything seemed fine for a couple of days until I noticed yet another puddle of gas on floor . frustrated I began reading posts and found that it might help to invest in some o rings ,so I put an o ring on the drain screw and that seemed to help for about another day but now im getting gas leaking from where the carb fits onto the intake manifold tube. what gives ? I just cant seem to get this leaky gas problem resolved .if anyone out there can help me id be very greatful . I have a stock carb on a cheap ebay 80cc bike kit. please help this thing barely has 5 hours of use on it.

  2. 074KU

    074KU Member

    Replacing the carb outright with something like a Walbro would leave you with the most hassle free solution, however it is slightly technically complex to install and requires you have access to a few tools.

    I personally have stuck with the NT carb (standard) and hear your frustration.

    Some of this you have already done, a Check list follows:

    - Replace fuel line.
    - Replace fuel tap.
    - Replace filter (not likely to cause leaks, although mine did)
    - Place an O-ring in the carb throat where it mounts on the intake manifold.
    - Drop the carb bowl and check that the brass prongs allow the float to shut off fuel (Stops the flooding I am guessing is your current issue)
    - Check the float for holes
    - Make sure your bowl and float are good and clean to avoid the float sticking
    - Make sure the fuel line fitting is in nice and tight (do not over tighten!) just a good firm nip
    - Check the gasket between fuel bowl and carb body (rarely this can be damaged from initial assembly or a bit dirty)
    - Check that your fiber washers are in good condition

    A little mod, place some longer screws back in the bowl and put a couple nuts on to act as lock nuts. This stops those damn little screws from backing out over time (even loctite 243 seems to fail over time in this situation)


    If you are still having issues after all of this, hit me up and I will try to help you out a little more.
  3. Fabian

    Fabian Well-Known Member

    Although i am a fan of the Walbro style diaphragm carburettor, there is nothing wrong witht the NT carburettor when jetted correctly.

    Having said that, the NT carburettor will always leak fuel and will always be covered in 2-stroke oil; collecting dust and grime to the carburettor.
    It's just how it is, and you will have to put up with the filth and dirt and grime, if choosing to use that style of carby.
  4. 074KU

    074KU Member

    I have pretty much managed to eliminate external fuel leaks from my NT carb, I have to give it a little wipe down every few months or so but it is certainly leaps and bounds beyond having pop the bike onto its rear wheel before every ride to drain the 2 stroke oil off the top of the bottom end. I can actually go for a month or so without anything beyond a film there anymore.
    determined likes this.
  5. butre

    butre Well-Known Member

    My NT carb never did a whole lot of leaking.
    determined likes this.
  6. 074KU

    074KU Member

    I think some of the NTs like any other parts in the engine kits get put together in a sloppy manner. I have had the odd NT that has been quite fine from day 1 others leak like sieves from parts being loose, damaged or dirty. I even had one which needed the needle replacing as it was so poorly machined it couldn't be saved (even with a whole machine shop at my disposal)

    End of that day that is Chinese QC for ya! But there is something I find very satisfying about taking something that barely works and getting it to run in an acceptable manner, its possibly more fun (sometimes) than riding.
  7. HeadSmess

    HeadSmess Well-Known Member

    its not just the NT. had plenty of keihins and mikunis almost hit walls after being dismantled repetitively. one or two i actually let go of at the zenith of the swing :) (three strikes and ill give it one more go but seriously im getting really fed up!...)

    if its fuel emanating from the intake/ airfilter/ flooding the engine... check needle valve for crud, wear and the float tabs for correct adjustment, no obstructions, etc etc.

    thing i hate about the flooding cylinder is it happens just when youre getting complacent, at which point it actually causes damage :willy_nilly:
    determined likes this.