I found this hose hanging out on the right side and can't find where it goes. It has a foam filter on the end of it. Any ideas? The hose to the fuel tank is connected.
This is on a 2000 SP 500.

 

Just trace it back down. Either has to be from the front diff vent or line from the radiator to the reservoir bottle. Or can be the vent from the oil tank leading to the air box.

 

Yep, I checked all those and they're all there. The tube comes from under the right front fender area and is zip tied to the frame. Just below the frame is the little grey foam filter on the hose end. Then it heads back to the rear and doesn't reach much farther than the carb. You got me. Maybe it's a beer vent.

 

Vacuum line to the carb from the pump hooked up? #4. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Beyond that I can't think of what the line is for if the oil tank vent is accounted for along with all the fuel lines,front diff vent line.. If you're not the original owner someone may have moved vent lines around or added one? Plus a foam filter on the end of it?? Doesn't sound stock to me.

 

Thanks OPT. I'm beginning to think you're right about someone added it and ended up just dangling there. In any case, I did get to find all the vents and they're all doing their job, so it wasn't a total waste of time.