check stator and CDI unit.My 03/ 600 has these issues which i am still fixxing through polaris warrenty.
The bike would run but when you givver gas she would die and pop like crazy.Its taken 1.5 yrs and finnally i think i found the real problem.Good luck and GIVVER

 

I am having same problem on my 99 335. Installed new plug,checked all filters, put some seafoam in tank, reved it, still no improvement. P.S. how would I get to the carb to check it out, too much stuff in the way. any help would be appreciated!!

 

Steven,

I do not know what year your sportsman is but from whatr I can tell the problem you are describing sounds like the same problem I had. If yours is only a year or two old the info below will probably not apply.

Your problem is probably not fuel, Electronic, air, or spark related. Believe me, I replaced a whole ton of Sh*t on my bike before I actaully found the problem. With 95% confidence I would say that your problem is a worn exhaust lobe on your camshaft. The 500cc Polaris engines are famous for it.

I replaced mine with a used one (along with a used Exhaust Rocker) that I bought off ebay for $120.00. It took me three hours to fix it myself (And I am not very mechanically inclined) with the aid of a shop manual.

I should be good for another 7 years!!

 

also check to see if your vent tube on your gas tank is pinched.

 

Check to make sure the foam around the air intake isn't covering the intake whole. I had this problem and it is a simple fix, but not easily identifiable. Let us know if this helps or if you need more explanation.