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Hey guys, been a while since i've been on here. I was wondering if i can get some help with an 01 sportsman 500 RSE i just bought. When i bought it the guy said it was hard to start, so i bought a carb rebuild kit and changed it, made sure everything was ok, and put it back on the bike. It is still hard to start. So while messing with i pull the air box and stuff back off so that only the carb was still mounted and tried to start it. Nothing happened it just turned over so i pushed up the jet needle and it fired right up. So i killed it and tried it again. It started right up without moving the needle jet. So i pulled the needle out and adjusted the clip down a couple of grooves and it started fine the rest of the day. Now it is doing the same thing again. What do u think is the problem. Also, it is backfiring through the exhaust loud when i try and give it a little throttle while cranking. The choke doesn't seem to help at all. Thanks for the info in advance.
 

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Dropping the needle clip raises the needle up and richens up the fuel mixture across the entire throttle position range. It is running to rich now and that is why it backfires through the exhaust. You need to put it back to the original position, take apart the carb and make sure the pilot jet, mixture screw, and all related passages are clean and clear. Just installing new parts doesn't get it clean.
 

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Also check diaphram on top of needle, may have a hole in it, what is air screw set at? should be 2.5 turns out , airbox needs to be on and sealed for it to run right, I could see moving needle clip down one but 2 is probably too rich, did you replace the jets with the kit? if not make sure pilot is clean, sometimes have to run small tip cleaner -wire thru it to get it clean. AQlso make sure choke plunger is working and clean .
 

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Discussion Starter #5
i did all that

I replaced all the jets, needle and seat, needle jet, and air screw. I set the air screw at 2.5. It was backfiring through exhaust before i moved the needle jet. Everything that i could see and spray with carb cleaner and blow out with compressed air was cleaned.
I checked the diaphram and did not see any holes or small tears. I'm just wondering if it sealing around the cap. The choke works as far as i can tell, I cleaned passage for it and the cable end.
I really appreciate all the help but i have done all the things that u are saying already. I just can't understand why when i lifted the needle jet by hand it fired right up. Idk, I will just keep playing with it. Thanks guys
 

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Hey guys,I got a Polaris 500 HO ATP given to me last week,want run been setting up for 4 yrs. no gas in carb,going to take carb off.Got the throt.cable disconected fine,can't fig out flat head bolts on choke cable box GRRRR!!!!!
Thanks for any help
Camgear
 

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My 2004 Polaris 500 Sportsman just quit while driving. It would start and idle, but as soon as I gave it any throttle, it would quit. Any suggestions?
 

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You should have started a new thread, but when you open the throttle to allow more air into the engine - if the carb does it's job, it mixes the required amount of fuel with the air and it accelerates - if no fuel is mixed with the air the engine dies - the carb needs to be serviced.

If you are using alcohol blended fuel and don't use it up within 30 days, it will separate into a layer of water/alcohol on the bottom of the tank with the gas on top - if the water/alcohol gets deep enough, it can get into the carb, block the main jet and act the same way.

Have the carb serviced, drain the fuel tank just to be safe, use non-alcohol fuel to avoid the phase separation problem, don't put in any more fuel than you will use in 30 days and shut the fuel off when the vehicle is stopped - better yet, drain the carb when not in use.
 

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There are several passages built into the carb body that do not come in the kits that need to be cleared out. Many of these ports are there for vacuum and so forth. I usually spray carb cleaner with the little straw and you will see where the carb cleaner comes out somewhere else on the body. After carb cleaner, I will use my air compression to blow air though all of the little passages as well. Also, all of the ports that the jets install into, those ports may have buildup, or gunk in them as well. so remove the old jets, and before putting the new jets in, clean those passages out with carb cleaner and compressed air as well.
Warning: there are 1 or 2 passages from what I recall that are closed off. when I sprayed carb cleaner in them, it backfired out the passage and right into my eye. when I clean them, any hole or pin hole in the carb, i'll put cleaner through it just to be sure I got everything.

Also, my 05 sportsman 500 I think has the same carb as yours. there have been a few times that when I put the top bell housing over the diaphragm, the diaphragm ring slips out of the grooves of the body thus causing it to bind up, and lose it's pressure and not work. SO make sure that rubber diaphragm is in perfect place when the top bell housing goes back on the carb and you put the 2 screws back in.

When you press the thumb throttle, does it move smooth all the way in and out? watching the diaphragm in the throat of the carb while you move the throttle closed to full throttle over and over, does the needle slide smooth, or does it seem sluggish at spots? It should close at the same speed from top to bottom. It is moves slower at a certain spot while closing, then it is binding.
 

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I bought a used carb off ebay. Cleaned it, sprayed it, and blew it out with compressed air. Installed all new jets and needle and seat. Wouldn't run worth a flip. I took the carb back off and soaked in the paint can carb cleaner for a few hours, blew it out, put it back together and it starts and runs like a champ. I adjusted nothing. I leave no ethanol gas in it for months at a time, and it always starts right up.

I always cringe when people start talking about knocking plugs out and adjusting things. The best thing you can do is make sure everything is really clean, and keep good gas in it. Mine sat from October of last year to April, I took it hunting 1 time in January. Never added gas until April. Just left the gas one and in the carb, and guess what, it started right up. Didn't even have to choke it.

Still don't. That was 2 years ago.
 
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