So here is the story... A few weeks ago I drove into a pond on my quad up at tall pines Atv park and my machine stalled and I was floating until my buddy threw me his winch. Let it sit for a few and it fired back up and ran fine rest of day. I noticed the next time I rode that under wide open throttle bursts it would let out a puff of smoke and smell rich. I replaced air filter (which was dry even after pond) just figured it was dirty. Changed the oil and put some seafoam in the gas. We then went the other day and did a dice run and I'm leaving smoke trails through the woods. Pulled my plug and its black and dry. I pulled carb off tonight to try and clean it out but just want to make sure that the isn't anything major wrong or anything I should be looking at. Machine only has 800 miles on it. Starts and runs great just now is smoking which wonder if is just from seafoam but why would plug be black and dry

 

Milky looking oil when you changed it? If not then may be the seafoam or could be a worn needle and seat in the carb.Smoking could be gas related,not oil. Rather than clean a carb,rebuild one so at least you can eliminate that as the problem. Even though it may be low mileage,all these years with ethanol gas can eat up rubber tips on carb needles.Polaris Sportsman 500 4x4, 2001-2013, Carb / Carburetor Repair Kit

 

No the oil wasn't milky at all. Was very dirty and seemed low but it was first time changing it this season. I pulled carb off it last night and fuel was almost gone so filled it up with ethanol free gas and that's usually what I run in it. Seems like it's still got good compression judging by pulling recoil and it runs really good

 

If you have a compression gauge,compression reading should be between 55-90 psi on average because of the compression release device on the exhaust. Some machines may go a little higher.At least that can tell you if the top end is still in good shape and hopefully not a piston or ring problem on the smoking. Plus oil smoking is usually on the whitish side,excess gas smoking usually a little darker in color. If a head gasket is leaking and burning coolant it usually will have a sweet smell on the exhaust.

 

My worry is that when I was floating in pond that exhaust filled up with water. I drained out as much as I could at the time and it fired right up after sitting for a while and draining but could water have gotten into Motor then and did something? Like I said I changed oil and it was not milky at all and I just checked it again today and still not. Fires right up and runs fine no issues but is still smoking really bad

 

Water on a hot engine can sometimes cause it to blow a head gasket and coolant can seep into the engine and cause this smoking. You can do a coolant pressure test to see if this is the problem. If it holds 10psi with no drop,then that may not be the case and may possibly be an internal engine problem,scored rings or cylinder causing oil to bypass the rings. I've had this happen on a couple that ingested water and the air filter was still looked clean and dry. Plus like I mentioned if coolant is burning,normally you can smell it through the exhaust.

 

So I did a compression test and it's right at 75. Haven't done a coolant pressure test yet but is 75 good enough to eliminate possibility of bad rings? And when I pulled plug it's wet and black and smoke smells like it's running rich. It smokes and high rev not at start up or idle. Could this possibly be a carb issue? Or anything else? It's a 2006 sportsman 500 ho

 

75 psi compression is well within range called for in the manuals(55-90) considering the decompression device on the cam. Yes I'd get the carb kit,plus here's a pdf section from the manual on this BST40 carb.https://www.google.com/url?sa=t&rct=...U2gGlaHJWSIlbA The float is the tricky part to set on this carb. Here's a good article on the BST40 carb used on a Ktm. Similar to the Polaris carb that shows how to set the float level correctly.The BST-40 Bible | Adventure Rider

 

So I tore carb apart and cleaned everything, put a new needle and seat in it. Got it all back together and it's still smoking like crazy and stinks. To me it doesn't smell like oil. It doesn't smell like a sled or a 2 stroke but is still smoking like crazy.

 

What color is the smoke?