Author Topic: carburetor - stuck float / valve  (Read 535 times)

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Offline dankeller

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  • 1978 xs500
    • toronto, on, canada
carburetor - stuck float / valve
« on: April 03, 2017, 06:25:51 PM »
Hi, I was wondering if anyone had a trick(s) for dealing with a stuck float or float valve without removing the carburetor from the bike.

In my case, I have found a couple of times that after draining the bowls and refilling them with fuel through the petcocks, fuel will run and leak out of the air box on one side, and into the engine crank case through the other side.  Left unnoticed, this will result in fuel flooding the crankcase, thin out the oil and make starting/running the bike impossible (oil too thin, and it causes cylinders to be too rich), requiring a complete oil drain and refill.

This has happened to me after getting the bike ready after winter storage, and a couple of times after running low on gas in the tank and switching to reserve on the petcocks.  And yesterday, I installed a small "aux" valve after the left petcock (owing to a leak) and ran the bike forgetting to turn on the aux. valve.

One time in the past when this leaking happened I had to resort to removing the carbs, turning them upside down and shaking them, and blowing with my mouth into the fuel lines to the carbs to confirm the float valve sealed, before carefully turning them right side up and reinstalling them and slowly filling the float bowls.  But this is a lot of work!

Another time, I managed to sort out the leak by draining the bowl with the carb on the bike and tapping the side of the carb with the soft handle of a screw driver as I filled the float bowl using the petcock prime position.

Yesterday, the tapping didn't work so I used a paper clip up through the drain hole to poke at the floats, and that eventually did work.  (I found a sweet spot when pushing up on the paperclip that when I blew air into the carb fuel line, with my mouth, I felt resistance; then I carefully removed the paper clip, filled the float bowl through the petcock; and was relieved not to see any leaking).

This must be a common issue to be experienced by others, so I was hoping to hear a good solution to prevent this from happening, and for fixing it when it does happen, from some of the more experienced xs500 drivers here.

Many thanks.

Dan Keller