Here is another carb problem, as if people haven't heard them enough. Mine starts the same way as most: I bought an 03 Bear Tracker from a 2nd party that tried to cobble it together for resale.
When I got it, it didn't run very well. I took the carb apart today, cleaned it up, and put it all back together. When I got it, there was no hose on the upper port that faces the airbox. It ran just fine before the cleaning without a hose attached there, but wouldn't go under any kind of load. It pretty much just idled. After the cleaning, now I have fuel shooting out of that upper port when I open the fuel petcock. What did I mess up, or where does that port connect to? I just assumed it was a vent since nothing was coming or going from it when I bought it, but now it fires fuel everywhere. Any bear tracker owners have any advice or a link that can help me? The previous owner DID put a new carb kit in it, so I'm scratching my head unless there is a hose that is supposed to be there but isn't. I've looked and looked and found no stray lines laying around and no ports from any items I removed that I may have knocked a line off of...

 

Your float needle has stuck open. I must have cleaned over a hundred carbs and in about a quater of them the float needle has stuck afterwards. Check you haven't filled the cylinder with fuel, then try to get the engine started, don't use choke, open the throttle wide and it just may start. Run until all the fuel in the carb has gone and it stalls, then open the tap. If it doesn't flood again you have won. If it does, or you can't get it started, you will have to remove the float, check you haven't assembled it wrongly and clean the float needle.

 

Merryman, thanks for the reply. I'm dealing with a carb that 2 separate parties had apart before me. The guy I bought it from said the guy he bought it from took it apart and didn't put it back together correctly. This guy claimed he did, but when I got it, it would constantly fall flat on its face under load. At idle it was fine, but in gear, it would die out. I took it all apart, and it seemed like the float needle was sticking. I used some steel wool and lightly rubbed it all the way around, and put it back together. It seemed to not stick closed anymore. But, it doesn't look like the float is at all adjustable, so I'm not sure where to go on this one. Any idea if there's a carb rebuild manual out there? I need to make sure I'm putting this thing back together correctly.

 

An exploded view is a good place to start 2003 Yamaha BEAR TRACKER (YFM250XR) Carburetor | International Moto Parts

It will be a Kehin or Mikuni so there will be U-tube videos of how to rebuild these carbs, just Google them.