The needle seat is held in by a plate on the older bst34 carbs,by the float assy on the new bst40 carbs. I agree the o-ring can seep,but might as well replace the needle and seat as a complete set while you're there. No sense in having to go back later. Polaris sell the needle and seat as a unit,the o-ring separately. Item #24-25. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse.

After market kits come complete with the o-ring and cost less than just the Polaris needle and seat in most cases. New Shindy Carburetor Carb Rebuild Repair Kit for Polaris Sportsman 500 99 00 | eBay

 

I recently rebuilt my carb also which is the same as yours bst40. I got lots of help from OPT too.....he's very helpful!
I had trouble with the float height also ,how to hold the carb and at what angle. Here's the trick......the float valve has a little spring loaded pin in it , so you slant the carb to an angle where the float tab (tang) just touches the valve (the pin) and doesn't compress this pin at all. (Take it out and have a close look at it) That's when the float should be in line with the carb body. You have to press on the plastic float *** too when checking the level.
It was confusing to me too when I turned the carb upside down and saw the float sink way down into the carb body bowl until I realized that the valve had that spring loaded pin in it!
Mine still drips a little , that seems normal for these bikes.

You do need 20 posts before you can add attachments. Until then , you can use photobucket and post a link here to it....

Kevin

 

[QUOTE=bgonzo;3157838]I have a 2003 sportsman 500, and the carb is leaking badly. It appears to be coming from a small nipple on the bottom of the bowl (about 1/8 inch diameter and 1/4 inch long). I will try to attach a picture. Is this a vent or something? I'm thinking the needle/seat might be leaking or the float is stuck. has anyone seen this? Is there a way to unstick it without removing the carb? Same thing is happening to me, I bought a new carb and it’s doing the same thing. Help

 

My wife buried this thing and then I started getting fuel leaking from float drain line, I cleaned carb reassembled same issue....it poured out. Replaced carb with a new one and same issue. Is there a vent somewhere that could possibly cause this issue. Thanks and Thanks for the add.

 

Reviving an old thread here. I have a barn find 1996 Polaris Sportsman 500 I am basically restoring. Engine compression tested fine so I went forward with working on it. Air box was shot, at the advice of another thread here, I acquired a complete 1998 airbox with filter and installed. Carb was shot. Opened it up, I was not the first. Parts installed backwards, mismatched screws, hollowed out screws, just a mess. Decided to try a Chinese knockoff carb to replace it. New fuel pump and lines, gas tank removed, drained, rinsed, reinstalled. New coil and plug, new CDI, new exhaust all the way back. Starts but runs poorly, need to keep hand over 90% of the air intake opening. There is a small spot where it seems to idle and run fine, can rev smoothly but backfire when I release the throttle. Gas drips out of the vent tube. Tapped bowl with a small hammer, seems to leak less but still leaking. I am not good with carbs, never have been. Considering trying another cheap new carb, carb kit for the one I have, or spend a considerable amount more on a better quality replacement carb. Words of advice? Hoping Old Polaris Tech is still on this site.