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Discussion Starter #1
Hi all. So I recently got a 97 sportsman 500. I had it running good. My daughter and I were ripping up the back yard with it. So finally had a day to go riding. Got to my buddy's and it acted like it was cold. So I figured I'd run it up and down his driveway a few times to warm it up. Well then it started to sputter and cough a little. So we pulled the carb and everything looked ok, but now as soon as I tap the throttle it splits and sputters. If I kind of feather it I can get it to go wide open but not very good. In my haste I bought a new carb but the issue is still there. Now the only thing different I did between my house and my buddy's is I filled up with some leftover 32:1 mix. Any suggestions. I'm going to check the exhaust to make sure there's no rats nest in it. I'm also thinking maybe the fuel delivery is weak. Oh and before it gets mentioned I have no air box, nor can I find one anyplace. So I had to make a pvc snorkel with a cone filter on the end.
 

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Discussion Starter #3
I know it's 4 stroke. My other machines are 2 stroke sports quads. So a care way more 2 stroke gas then 4 stroke. I've never put that mix in a 4 stroke before. Usually chainsaw gas in my riding mower.
 

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I'd check that plug its probley fouled out badly. They cant run with extra oil in the gas. Check that and do a compression check make sure it's not low from a sticking valve or bad ring. The spitting and sputtering on mine was the ignition coil going out.

Sent from my SM-S367VL using Tapatalk
 

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How 'left over' was the fuel and was it pure gas or ethanol blend? Oil will not mix with ethanol and it will cause the ethanol to separate from the gasoline in a very short time, but ethanol will mix with water - in fact it attracts water - if the fuel was over a week old the bottom of the gas can was probably a water/alcohol mix. Try draining the carb and fuel tank and put some pure gas in it. Other than that maybe try a new spark plug.
 

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First/easiest thing to check would be fuel delivery as you mentioned.
Ensure your fuel Tank has enough gas in it and the petcock is either on Reserve or On.

Pop off fuel Inlet to your carb. It should be the one on the right side of your carb coming from the fuel pump. Be sure it’s the not the pulse line. The pulse line is marked on the fuel pump with a “p”.
After you pop the fuel line off, give the atv a few cranks (with the fuel line aimed in a safe direction, preferably into a catch can). You should see the flow increase substantially and will probably have a pulsing action; if it is just a dribble, that’s not enough.

Report back with your findings, and we’ll proceed
 

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Discussion Starter #8
Thanks for the good info. Haven't been out to the garage in a few days. New pump should be here today. There was poor flow and it didn't increase much when I hit the starter. I'm also going to put a new pulse line to the new pump. Figured crossed. Oh and I'm going to drain the tank.
 

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Sounds like you’re close to resolving the issue. Lastly, when you have the tank off, remove the fuel outlet nipples on the bottom of the gas tank and clean them out with compressed air or brake cleaner. Mine were gummed up before too. Be sure to only remove one at a time and mark your fuel lines to ensure everything goes back in the correct place; if you get these mixed up, your petcock will draw from reserve when in the on position (and visa versa), which could result in you being stranded on the trail because you actually sucked your fuel reserve dry when your petcock was actually in the on position.

Anyways, I’d be willing to bet that fuel pump will solve your issue. Be sure to let us know how things turn out!
 

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Discussion Starter #10
New fuel pump didn't fix it. Fresh tank of gas. New lines. New carb. Still will not run well. Thinking maybe timing. Going to check valve gap.
 

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while you’re on the fuel subject, try opening the bowl drain on the bottom of your carburetor to make sure that fuel is making it to the carb. Could be a stuck float needle.

If there’s fuel in the bowl, the next thing to check would be the pilot jet to ensure that it’s not plugged. This is pretty easy but does require the carb to be removed from the atv.

Spark intensity is extremely easy to check. I could also give you a walk through for that if you’d like.

i wouldn’t be too concerned about valve gap at the moment. I highly doubt that’s your issue.
 

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Discussion Starter #17
Yup. All new. But that still wasn't my whole problem. So I had to disable the Rev limiter. Just a black wire on the circuit panel. A lot of carb fiddling and head scratching. Took off the Lowe's fuel filter and it runs 98% better. Now it's just fine tuning the cab. Sucks having multiple things wrong at once. Kind of has you running in circles untill you can get things nailed down.
 
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