Just got back from spain with my multistrada and an st2, awesome week's riding however couldn't help noticing that when the ST was filled with fuel and then left for a few minutes it seemed to be venting fuel through the filler cap lock!!
I am guessing that a breather must be blocked somewhere, has anyone else ever had this problem??
Bikes: MTS12S, R1, off road stuff, and vintage stuff too.
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sounds very odd. My st4s has never done this, but will regularly leave a puddle from the vent if I overfill it. I'd be checking the pair of filler vents. There is one which vents from around the outside of the filler neck. The other one vents from the top of the tank. Its unlikely this has dropped off else you would get fuel all over the place even when the tank wasn't full as the pressure builds up inside it (ask me how I know <roll eyes>).
The best way to check all the internal tank pipes is to remove the fuel pump & sender unit out of the bottom of the tank. You obviously need to drain it to do this. Unbolting the filler and lock won't show you anything.
Make sure the moving part of the filler cap is nice and tight when its shut. You may need to swap washers around under the lock part to get it to close up a bit tighter. Leaks from the cap tend to be more obvious when the bike is on the side stand.
My ST2 has never leaked form the filler, but i am aware that when filling, the fuel level must never be above an inch or two below the internal neck. If not, fuel is deposited on the road via an overflow pipe below the belly pan. I seem to remember reading somewhere that this is normal, but it is a right pain as you never know exactly how full you can get away with, and of course you can never brim it for maximum range.
one note, if your going to take the tank unit out, make sure you have a new sealing ring first, changed my filter this year, and lo didn't i just nip old seal putting back in, cue major leak when filled back up as i didn't spot it and 160 mile trip to get a new one with bike in bits in back garden. they're only about 7.14 so worth having around just incase
05-Jul-2009, 14:08 
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