Hey Prairie 650 owners. I think I've read some posts about oil in the air box and some other overflowing oil problems. My dealer told me, on delivery. ALWAYS shut the fuel petcock off when I'm not riding the quad. He said that if one of the pistons is down the large cumbustion chamber, sucks fuel down into the engine and causes the oil to overflow into the air box. I guess they had a similar problem with one. They said it didn't hurt the quad, but it made one big mess and they had to clean the quad up.
I don't completely understand the problem, but the gas is not gravity fed, it's working on a vacuum since the tank is in the rear, so it made sense, that it could happen.
Just thought I'd share the dealer's comments to ALWAYS shut the fuel off.

I leave mine on.

That never happened to me. I had a lawn tractor do it, but that was a stupid lawn tractor.

I think some people's quads may have a defective air somethin or other widget valve that equalizes air in the tank. Maybe that doesn't make sense? I guess I don't know how gas could keep going down the carb. My tank never has pressure or vacuum, at least I've never noticed any.

I got a little oil in the airbox once, but it was because I put too much oil in.

Anyone have any idea why gas would keep flowing down the carbs unless it had a bad needle?

The only time I turned my gas off is when I was wondering how long it would idle with it gas off. Evertime I open my gas cap it has some pressure in the tank, but it has never caused a problem, no gas leaks, no oil and excessive gas in the air box. I have noticed that the more gas that is in the tank the less pressure that it has.