had this quad 2 years, problem just started this weekend. starts and idles fine, will allow full throttle in park. put it in gear and try to drive and it has no power, like it has a miss. pulled plug and it was coated black. replaced plug and put seafoam in tank. also sprayed seafoam directly into carb while running. still same problem. however, when i remove airbox it runs like normal. I'm leaning toward carb running rich,,,any thoughts?? thanks

 

If you have to remove the air box to make any Polaris run right,then it is too rich. Could be float sticking or worn needle and seat.I wouldn't just clean a carb,replace worn parts. BST40 carbs didn't change much over the years but I'd check the jets in the kits against yours.Polaris Sportsman 500 Carburetor Repair Kit Fits 2001-2002 Carb: Shindy 03-408 | eBay Probably wouldn't hurt to check valve clearance while you're at it. .006 intake and exhaust. Plus the float setting is critical on this model. Float parallel with carb body and float tang resting on needle plunger.

 

Hey thanks for getting back to me! I work on a lot of my own toys, but have never tackled rebuilding a carb on a polaris. Is it better to just buy a whole new carb? Also, why is there a fuse marked EFi? Is this model TBI? I feel comfortable changing the whole carb. Also with the valve adjustments, whats involved with that? Like i said, im not afraid to tackle any project.

 

Do you have a carb model or an efi with a throttle body with injectors?? Easier to rebuild the carb with a good kit than to replace with a cheap Chines knock off carb. Efi has it's own set of problems. Here's both manuals for a carb model and efi. Find out which one you have.2012 Polaris Sportsman 500 H.O. Service Manual PDF Download 2012 Polaris Sportsman Forest Tracker 500 EFI Int'l Service Manual PDF Download The manuals are the first step to get for any machine if you intend on working on them..

 

If it's an EFI it would probably have an EFI sticker on both sides of the headlight pod like my 2008 does.