A couple of days back I noticed my 2011 Yamaha Scorpio had begun leaking fuel whilst parked up.

Upon close inspection it was just a slow drip coming from a tube near the rear of the bike.

After searching around it appears that I may have a "stuck float".

I've tried tapping the fuel bowls with the end of a screw driver, but I'm either not rapping them sharply enough or it isn't doing the trick.

I'm not very mechanically minded, nor do I have many tools to try taking the carburetor off and fixing it myself - so before I take it in to get a mechanic to take a look, is there a way to stop the leak?

I tried turning off my fuel line before, turning the dial from on to off, however after an hour this had little to no effect on the dripping coming from the pipe.

Is there anything else I can do in the meantime to prevent the leak before getting it looked at?


This is the pipe that is leaking:

Leaking Pipe

And this is where it feeds in to if I trace it back:

Source it originates from

  • I picture is a worth a thousand words. Can you take a pic of the tube that is leaking? Have you tried to trace the tube? @Sameerariff has an excellent suggestion. If your float bowl is getting flooded, tapping it vigorously with the handle side of a screw driver can get the needle and seat to 'fit together' again and the leaking may stop. Jan 30, 2016 at 16:32
  • @DucatiKiller I have added a couple of images. Just to be clear, which part of the carburetor is the float bowl?
    – James
    Jan 30, 2016 at 19:47
  • @James In the second image you have posted you can find the float bowl, which is a rectangular tank connected to the bottom of the carburettor with the screws facing down. Jan 31, 2016 at 4:07
  • @Shameerariff Thank you, I'll try getting at it again with a screw driver and failing that I will try taking it apart. Worst come worst I will just take it to a mechanic as I don't have many tools or much experience when it comes to mechanics.
    – James
    Jan 31, 2016 at 4:14
  • @James You do it with the confidence. It does not require much tools, So you can do it. Keep update the status, and reach us if any support is needed. Jan 31, 2016 at 7:05

2 Answers 2



  • A float gets "waterlogged" (so saturated with fuel that it just won't float anymore.)
  • The float could be bent in position.
  • Worn tip on float needle
  • Worn o-ring in the float seat
  • Excess dirt and varnish in the carburetor. (Varnish deposits occur when fuel sits too long..)

The best thing to do is remove and examine the carburetor. Take it apart, clean up all the gunked fuel (varnish), test the float, adjust it as required. Examine the float needle and seat and rebuild as required. The fuel level should be between 2.7 and 4.7 mm below the float chamber casting split line.


As you doubted the trouble was with the float.

  • I would like you to remove the bottom cup of the carburettor and remove the fuel and gently blow some air to the float and to the jet. Make sure not to disturb the Air or Fuel Screw. If you disturb it, it will be the difficult task to tune it back to normal by you.
  • Now gently tap the float and make it free. Make sure there is a fly needle which will hold the float in its position.

Fix back the bottom cup and wait for a couple of hours for the leak. If you find again then check the gasket of the bottom cup as well as the o-ring overflow screw.

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