I have a 1997 Polaris that I just had the engine rebuilt on, and I got it in yesterday. I am in the 2nd hour of breaking it in. It runs great driving around slow to break in, but when it is at idle and I give it a little gas to rev it up a little bit it seems like my throttle sticks and will not go back to normal idle and when I try to give it more gas to get it to break free it raises the idle even more, and when I hit the kill switch and turn the key off it will stay running for a good 15 - 30 seconds before it shuts down. I am not reaching a point at idle to where it is red lining or even close the idle is just alot higher than usual and it gets higher each time you tap the gas to try to get it to stop. This never happens when the four wheeler is in gear. Please help I want to get my next 2 hours of break in done today.

 

Check your cables to be sure they arent binding any where and a good oiling the inside wont hurt.And check all the connections on your carb for air leaks.

 

Sounds like your throttle cable may not be sliding freely. Your cable needs to be lubed from time to time. You can disconnect it from the throttle housing on the handle bar and then use some wd40 with one of those small spray tubes and squirt it inside your cable line. Work the throttle while you're doing this to get the cable lubed up.
Also another place the cable can get gummed up is where the throttle cable and oil pump cable meet (that's if you have a 2 stroke). Where the cables come together I drilled a small hole in the plastic junction piece just big enough for the spray nozzle from the wd40 can and then I sprayed wd40 directly into that slide piece where the cables meet. You just need to drill thru the top of the plastic cover not all the way thru both sides. Then you can use a little drop of silicone sealer to cover the hole.
This made my throttle cable really work smoothly. Also make sure you cable is adjusted properly where it enters the top of your carb. Make sure it is adjusted there so that it can get all the way to the bottom of the carb easily. Sometimes if the cable isn't routed correctly it makes the cable bind and not slide easily also. If you had the plastic and the tank off you might want to double check and make sure the cable is routed correctly and not getting pinched or kinked somewhere.