I know exactly what you're talking about.
I have a TW200, it's a Yamaha enduro bike that has giant fat tires. It sits a lot lower than most dirt/enduro bikes, so I can sit on it and have both feet flat on the ground. Makes for a fantastic way to explore ATV and snowmobile trails, and all the seasonal roads up here. Truly a blast to ride, like a mini-bike for adults. I put in a bigger main jet a couple years ago, since they tune these things so lean from the factory. Lean helps with emissions, but it runs way better with the 130 jet installed. So either while doing that, or maybe just age (it's a 2009) I've had an issue with the float bowl overflow dripping when the bike isn't running. That little float valve seat isn't holding, and it's enough of a slow leak that it'll fill the carb bowl and drip out the overflow tube. Funny, it doesn't happen while the bike is running, so the leak is less than the amount of gas the engine is consuming, but when it's off, drip......drip.....drip. I have the parts to fix it, and pulling that carb isn't a big deal since it's a single and the rubber boots are pretty flexible, but just haven't done it yet. I've gotten to where I just shut the petcock and let it run out when I'm done riding it.