Carbs won't stop leaking

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    Hi everyone,

    I frustrated and hope someone has an answer that can help.

    I’ve been riding my newly finished ’79 and I just can’t get the float bowls to stop leaking.  They seem to leak from the corner of where one of the float screws holds the bowl to the body.


    I’ve had problems with threads stripping out because the previous owner messed them up. In those areas I’ve had to drill and tap for an M5 screw.  This makes me not want to overtighten all of the screws. They are snug, though, and shouldn’t leak.

    I am using OEM float bowl gaskets, new needles and seats.

    I did notice that if you put on the float bowl without the gasket, the bowl does not sit flat on the bottom of the carb body. The emulsifier tubes actually hit the shoulder inside the bowl where they slide in.  I tapped them into place so they are as far in as they can go.


    I also checked on a spare set of carbs I have and they sit the same way, so it’s not a defect.  The gasket is meant to take up the gap, I guess.

    Has anyone had a similar problem?  Anny suggestions? Do you think putting on 2 gaskets would help?



    The fuel level should not be that high, so it sounds more like a float,float height,or valve problem.


    Though you do want the bowl snug to the carb and a good gasket those are really just for splash seal.  The level of gas normally should be just below that line.  Sounds like you need to retest your float seal and level in the bowl.  On well worn seats of older carbs a solid polishing and float needles with viton tips can make a world of difference.


    Definitely no to using 2 gaskets, this would solve nothing. As Marksav says the fuel level is to high. This could be because the floats are not set correctly or because the float valve isn’t working properly. Check them and reset/replace as required.


    Thanks for your replies, everyone.

    I have checked the float heights using the appropriate fuel level gauge a(clear tubettube that screws into bowlabowl drain screwascrew)s at the appropriate height. Actually, they are at the lowest of the height settings, so they are well below the lip of the carb body and float bowl. Actually, one float was set a tiny bit too high, so the fuel level was low causing the bike to starve for fuel at top gear and high speed.

    Also, float needles and seats are new.

    Baffling, isn’t it?

    I just got something called Hylomar Universal Blue sealant. Gas resistant, used on aircraft, non-hardening. I’m going to try a thin coat on the gaskets.

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