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There may be a piece of junk poking through the seat, preventing the needle from seating.
While the float and needle are out, blow some compressed air through the fuel inlet to the carb.

'Course your needle tip might be stuffed, as mentioned by Rob.

Weighed the floats today. 15 grams.

Chuey

Maybe modern fuel doesn't turn them so yellow anymore?

Did you ever replace them? IOW, know their age. I always tried to remember to shut off the petcock a few blocks from home/work so the bowls would be fairly empty when it sat. Part of the joy of owning an older bike.

15 grams is just about the limit of being usable without overflows but the floats must be set 2 or 3 mm lower than parallel and if you check the setting by measuring fuel level in a removed bowl aim for 2 or 3mm lower than normal other wise it will give a high operational fuel level. I ran like that for years before they finally became sinkers. On the other hand I probably should have replaced them sooner.

OK, then. Tomorrow, it's a trip to the dealer in Escondido to try to buy new floats......two carbs worth. Man, this is a bit heavy for me. It's one day before the anniversary of my off bike 75mph break dancing on the freeway adventure. (All motorcycles are adventure bikes!). I was coming back from that dealership when it happened. I may drive my Saab this time!

Chuey

Have you tried lowering float level and had a good look at the needle tip and blown out the inlet passage?
No point spending money on something that may not be the cause of the leak.

Last night after I read a comment about a gas soaked boot from Chuey, the cause flashed in my mind. It has to be the float weighted with gas. It is at the point where it's just about too heavy, it will hold the needle shut when the bike is stationary and being run. But as soon as you ride and start sloshing fuel around it can't stay up or move fast enough to shut the fuel supply.

jagarra wrote:Last night after I read a comment about a gas soaked boot from Chuey, the cause flashed in my mind. It has to be the float weighted with gas. It is at the point where it's just about too heavy, it will hold the needle shut when the bike is stationary and being run. But as soon as you ride and start sloshing fuel around it can't stay up or move fast enough to shut the fuel supply.

Could a gas soaked float be checked by allowing the float to dry out and reinstalling?
Sounds like this problem came on quickly, and now produces a major leak. I can't see a float suddenly becoming soaked and causing a major leak.

ME 109 wrote:

jagarra wrote:Last night after I read a comment about a gas soaked boot from Chuey, the cause flashed in my mind. It has to be the float weighted with gas. It is at the point where it's just about too heavy, it will hold the needle shut when the bike is stationary and being run. But as soon as you ride and start sloshing fuel around it can't stay up or move fast enough to shut the fuel supply.

Could a gas soaked float be checked by allowing the float to dry out and reinstalling?
Sounds like this problem came on quickly, and now produces a major leak. I can't see a float suddenly becoming soaked and causing a major leak.

No, it isn't sudden, it's a "tipping point" in a long slow gradual process.

jagarra wrote:Last night after I read a comment about a gas soaked boot from Chuey, the cause flashed in my mind. It has to be the float weighted with gas. It is at the point where it's just about too heavy, it will hold the needle shut when the bike is stationary and being run. But as soon as you ride and start sloshing fuel around it can't stay up or move fast enough to shut the fuel supply.

You can just imagine them bobbing up and down in the fuel with little buoyancy. When taking that pic I posted earlier it was quite hard to keep the float still.

I can tell you they don't dry out and get any lighter in the short term. I dried mine for weeks and they were still heavy. I have them on the shelf more than a year on so perhaps I should weigh them again.