Cycle the kill switch off and on several times,plus check the connectors and wiring into the switch. Yes control switch contacts can get dirty. Sometimes you can spray a little electrical contact cleaner in the connector and switch ends along with into the switch body and solve starting problems.

 

I finally got it going, it was the pickup coil.thanks for all your help.would the pilot screw being out of adjustment cause it to only Idle off choke and only rev up when u feather the gas or pull choke out a little and feather gas? Idles just fine though.i forgot to mention I cleaned the carb and I tighten the pilot screw down and then backed it off two and a half turns

 

Pick up coils are getting to be a common problem on the 500s. 2 to 2 1/2 turns should be okay on the fuel screw as it mainly controls idle an up to 1/4 throttle,but if you have to feather the throttle to accept fuel,then it's possible just cleaning the carb doesn't always help. Could be the needle and seat are sticking ,float level off,trash still in jets,etc. Carb kits are the best way to go and you can eliminate the carb as a problem area.Shindy(made in Japan) and Moose are good kits.http://www.ebay.com/itm/POLARIS-SCRAMBLER-SPORTSMAN-500-4x4-CARBURETOR-CARB-REPAIR-REBUILD-KIT-2003-2005-/161451430229?pt=Motors_ATV_Parts_Accessories&hash=item2597415155&vxp=mtr Plus not a bad idea to look at this post on the BST40 carb. Similar to your carb but used in a different application on a Ktm. Float level adjustment is critical on this carb and the pics show how to adjust it along with basics on internal parts.The BST-40 Bible - ADVrider