Sportsman 500 HO carbureted was running really rough, surging, missing. Had rebuilt the carb once, and thought it was the same issue. Rebuilt it again. No improvement. Finally found choke cable was sticking and flooding motor. Knob moved but did not move enrichener. New cable $60. Rigged it. Cut outer sheathing of cable near side panel so cable would be straight to carb. Exposed inner cable and now operate choke simply by grabbing cable with fingers and pull to choke; push to offchoke. If you have a motor running like crap check the enrichener before tearing out the carb.