I had just gotten my jetting set up the way I wanted it. My 400l sport was running great. THen I went riding on a day that was about 65 degrees. After about 20 minutes of riding the sport seemed to be flooding out. I figured it was just the temp change and loaded it up. I fired it up the other day about 85 degrees it did the same thing. My polaris dealer said it sounded like the needle and seat????? had worn down. It runs fine for a few minutes and then sounds like it is running extremely rich. Havent replaced the part my dealer said they thought was worn out. Just looking for some opinions. Thanks ahead of time for your help.

 

Anyone help?? I replaced what is, I believe the correct name is needle valve, and still that same thing. Off of idle any amount of throttle kills the motor. Messed with the clip on the needle, nothing. Dropped down a jet size and nothing. ANY ideas?????

 

mine was actually doing the same thing, i think u might wanna check out ur airfilter cus thats whats wrong with mine or was what was wrong with it.

 

Well here goes. I had the same problem with mine also. Thought it had ran out of gas actually so I flipped the fuel switch to reserve and cranked it a few times and presto, it fired up and had no problem for the rest of the day. Got back home and I took off every fuel hose on the damn thing and no cloggs and no trash in the filter. Had the same problem the next time I rode it and again I just flipped the switch and had no more problems. I finally used what little brains I have and pulled off the fuel selector switch and found out that the reserve side was fine but the regular position was clogged. That's why it wasn't getting any fuel and just bogging to the point completely stopping. This could be your problem, but here are a few other things that you can check:
Fuel filter plugged ( sometimes trash can settle in the bottom of the fuel filter or even the carb for that matter and the swishing motion caused by riding can stire it up enough to clogg up the line even though the trash never actually makes it through the line)
One of your carb vent lines could be pinched or even the tank vent line. Make sure when you check them that you check the entire lenght of them to make sure they haven't melted closed against a hot object.
You could check for air leaks also. Once metal gets hot enough, it can expand enough to cause seepage via a gasket. Spray a little WD-40 around the engine and also the airbox where it connects to the carb and listen for any change in rpms.
Pull the carb off, pull it apart and clean the whole damn thing again and give it a good blast of air where appropriate.
None of this may solve your problem, but it will eliminate a few potential ones. Good luck and let us know how it turns out and how you solve it. Enquiring minds want to know and be in the know.

 

Also, I would think that if there was a problem with your needle and seat, that there should be fuel running out of the carb overflow.

 

If you have problems from 0 to 1/8 throttle, then you may need to adjust your idle mixture screw and problems between 1/8 to 1/4 throttle might be adjusted with the low speed pilot jet. So if you're having problems from 1/4 to 3/4, you might want to look at the needle. The the main jet controls from 3/4 to WOT. If you send me an email addres, I got an article I can email to ya that might help you out in regards to jetting. It explains it in plain English. Hope this helps. I know you already said you changed the needle, but what about the low speed pilot jet? Even so, I still think it's a trash problem.
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OK, here it is. I tore the carb all the way down AGAIN. Think I might be a pro at that before too long. Set everything exactly the way it was before I had problems. Needle clip 1 to the rich side main jet at 260 and needle jet at stock 35. Nothing happened. So I blew out all the lines just to make sure that there wasnt any clogs. Then picked up a new throttle cable, single line instead of the dual since I have the oil block off. Pulled the plug and slapped in a new one. Presto. All better. Not for sure exactly what the prob was but by the end of it all I had fouled a plug so I had to change it out.