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Polaris 500 sportsman give it gas stalls

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All I have been through everything. Bought brand new.

Throttle safety switch 

Cam and rockers




Fuel safety switch 


Everything every forum has spoken of I've bought sealed airbox completely tight unplugged black wire on trans. I have literally done everything in the book.Checked oil today full of gas anyone no anything what might b wrong. Next I'm taking head off and making sure valves seat any ideas.

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A leaking valve isn't going to fill the oil with gas. Plus you can check valve leakage with a leak down test with the head on.

I would be looking at the carb. The needle and seat is not working right and I bet the seat of the needle is leaking. I posted about this problem recently on here in the Polaris forum. Booth units I had that problem with were Polaris 500's.

Be sure to pull the oil drain plug on the bottom side of the crankcase to drain the oil from the crank case. Just draining the oil from the bottom plug of the oil tank will not empty the crank case that is full of fuel.

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No it starts and idles perfect but when you give it gas it starts backfiring through the card horribly bad and it takes it forever to start keep turning it over it will pop a few times then it will eventually start and idle smooth as rain until you hit the gas replaced everything you can think of still same thing and its perfectly in time I don't understand it how can you do bleed off to check the valves with a compression tester

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No that's the only test I haven't done yet been reading all the forums so figured that stuff was what was wrong its doing same exact thing so didn't put much thought I have checked time and its smack dab on so I'm stuck besides compression check and make sure valves are seated. I have a top end gasket kit just blows my mind cause any other 44-wheeler main jet or sec jet is clogged I went over this one with a tooth brush so not sure where I went wrong 

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If that compression is what your showing the the only way at this point for fuel to get into your crank case is from a carburetor leaking fuel into the cylinder head and it’s making its way down the cylinder walls.  It has to be. Maybe separate the carburetor from the engine leaving it completely hooked up but pulled away from the manifold connecting it to the cylinder. As if it were in place but pulled a bit away from the engine.  See if you  notice any gas dripping out of the carb where it connects.  I would put a small piece of cardboard under it since cardboard shows moisture right away when it’s wet with the dark brown spots.   



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Not too sure about your make of quad but the Yamahas have a mikuni carb.  The brass plug which contains the seat has an o-ring around it which breaks down eventually.  This causes fuel to bypass the needle and seat and can flood the carb.  Notice any fuel in your air box?  Also the high compression readings make me wonder if you are partially hydro-locked.  If possible pull the seat out and check for that o-ring.  It happened on my 03 Kodiak.

Edited by Laval
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Had a similar issue with a Kawasaki once.  Crankcase is full of gas as a symptom of hard starting, so that's easily resolved once it starts correctly.  That compression is also a bit high so that's odd.  It's either a carb issue or bad plug. If you haven't replaced the spark plug yet, do that.  That ended up being the issue with my Kawasaki.  The plug wasn't firing hot enough under compression. 

You said new carb, I assume chinese carb?  Those are ok but hard to tune.  Sounds like wrong jets.  i've used 4 chinese carbs this month and jets were way wrong in all of them.  I had one stamped 95 that was NOT a 95, it was more like a 115.  Could also be the idle air screw wrong, float wrong.  Try checking the float level and using the OEM jets if they will fit.

Edited by MarkinAR
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I don't care if the carb is brand new. You have a leaking needle seat like I and the previous poster mentioned. Your compression tests are extremely high because the motor is flooded with fuel and almost to the point of liquid lock, further cranking of a liquid locked motor can also cause rod bearing damage and failure.

The needle and seat will be where it's supposed to be yet it is not stopping fuel from flowing from the back side of the seat where the o-ring that is suppose to seal and hold the seat in place. If you take the needle and float off and the seat is easily pulled from the carbs body it is leaking. 

Even a good sparking spark plug will not spark when the carb is delivering too much fuel.



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So I was checking it out today and watching videos while I had flywheel off well in the video the key for flywheel is straight up and down with top end end the flywheel theres three notches and back behind them theres a t I didn't know that I ligned it up with the middle of the 3 notches so do I line timing up with t instead I lined it up with the t but I'm curious so I'm asking b4 I try to start it cause if I do it was like 40-45° out of time

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Well put it 100% in time got the compression down to 138-140 but that's all it did still doing the same exact thing. Question though will it still give gas to the carb if your not turning the bike over like if I take gas line off to the carb gas still comes out. I checked the carb it is not leaking gas any where pulled the spark plug and nothing blew out of it it's not getting liquid locked at all. So I'm tearing the head off of it today to take s look at it. I lashed all the valves at .006 just figured I would ask you guys if it sounds right that's what my book says.

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Yup undid the little screw and pulled the seat out looks great. I got the head off right now taking a look at it. I'm damn good at fixing quads I do it almost every day but this one has me horribly baffled I no why gas is getting in the oil I have to turn it over about 50 times for it to start but when it does idles perfect when it doesn't start I pull spark plug nothing is coming out of spark plug whole its just kind of a little damp like you start it. Got the cam out now I didn't by rockers just the cam now the spigot and not sure what it is is it supposed to snap back really fast or just put in just for it to work when I put it in I spun the spring around once so it was a little stiffer but not sure if that's right

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