A-ARON

okay I have 2 Suzuki quadrunners that I have gotten in the past 2 days. im not sure on year on either of them. one is a 250 4wd, I cant keep the thing running and it has a new carb on it, once I get it to crank it will run about 30 secs and die. I have made sure that its getting gas and spark but still cant keep it running. the other I was told it was a 300 and its just 2wd and it has a rebuilt carb on it and it will crank up fine but doesn't want to idle at all