we have a 99 sportsman 500 and a 97 sportsman 500 we parked the 99 because it has no power, and only goes thirty tops. recently my 97 has no power, will not spin tires and is slow. likely the same problem with both. i poured seafoam in my 97's carb and gas and it practically ran on the stuff. i took i for ride and power was there again, it worked great. the next day i started it up and it had no power again!!!! its so frustrating, what do you think's wrong with my quads?

 

Have you gone through the carbs first? If the atvs have been sitting up or have old fuel without any fuel stabilizer, could be the problem?. OPT

 

we went through the carb on the 99, adjusted and soaked it in chemicals but nothing has worked.

 

just double checking so don't get mad, did you remove the jets and physically cleaned them till you saw daylight through all orifices on them and down the center?