Fuel leaking down side of carb on 98 yz400f

5 replies to this topic
  • Wanny14c

Posted July 24, 2015 - 07:56 PM


So I tried looking in the search and found nothing. I washed my 98 yz400f 2 days ago and a day later I noticed that fuel was building up around the outside of the bowl and dripping, not a ton but enough to notice it's like it's coming from above the bowl though. I have no idea what I'm looking for this is my first bike. It's on the left side of the carb as if you are sitting on it I think unless it's running around the carb and building up on the one side. Also my idle nob will not turn. Please help. Thanks

  • Goonyz400f

Posted July 26, 2015 - 09:07 PM


I dunno what the problem is but I've seen this on a couple of ones myself when I was looking a yz400f,what country are you in?

  • Noah Hildreth

Posted July 26, 2015 - 09:28 PM


It's likely that it could be that the float is stuck which is allowing it to fill up to the point where it overflows.

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  • Wanny14c

Posted July 27, 2015 - 02:38 AM


I am from America. The weird thing is it starts with no problems.

  • grayracer513

Posted July 27, 2015 - 03:20 PM


Nothing weird about the bike starting with a fuel leak.  On the right front corner of the float bowl is a roundish chamber wherein lives the accelerator pump diaphragm.  These will tear and leak gas up around the shaft that rises vertically from the pump housing.  This would be where I looked first.

  • buildabike

Posted July 27, 2015 - 04:01 PM


The idle knob is attached to a tube which is attached to the idle screw on the other side of the carb.  Might just try spraying some kine of penitrating oil on the idle screw.  The knob on mine is bent a little which makes it hard to turn.  You might look at that too.

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