This bike has 1100 miles on it . idols good ..when giving it gas or holding the throttle at full the bike sputters , does backfire a little . Wont hold high RPM. Have put new fuel filter, cleaned carb- didnt remove main jet .Air filter is cleaned --the fuel pump is cleaned ... Have been able to get the bike to run good when I strip the front plastic off to the frame . Have been able to get it to run good on and off . Also having problems with the throttle cable to idol when turning the steering idol can go up and down .

 

Adjust slack at the thumb throttle to where you have 1/8" slack only. You probably have it too tight or the throttle cable is in a bind if the idle changes.Check for any kinked fuel lines. Check the fuel flow by pulling the line from the carb and cranking the engine over. Should be a steady pulse of fuel from the pump. If not could be a fuel valve or pump problem.Also check that the fuel tank and carb vents are open. Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

Have done all that .still no change .idols good -about 1/2-to 3/4 throttle rpms start to go down the higher the throttle goes . Have been reading other posts and still cant figure it our . still wandering ...

 

If you're sure the carb jets are open,fuel flow is good,air box inlet tube isn't blocked by the foam support,fuel tank and carb vents are clear,the valves are at .006 intake and exhaust,then it could be an electrical problem. The Sportsman 300 was only made from 2008-2010 ,but I've found a pdf manual that might help you trouble shoot any problems. It's a 2009 manual but should be of help as they are basically the same over this period of time. http://www.mediafire.com/file/zywj1wkkhng/9921820.pdf
If this doesn't work you can download it here. http://www.partshark.com/custompage3.asp?pg=polaris
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