So I have an 01 polaris sportsman 500ho and a few years ago it randomly quit running. Got it out this winter, rebuilt carb, new spark plug, and fresh air filter. The machine is getting spark, and i checked the fuel pump and that seems to be working as it should because there is fuel in the carb bowl, but it will not start. Crank and crank with a battery jumper on it and it wont fire. Tried to pull start, same results. I adjusted the valves to spec, and checked the timing, and the cam gear was still marked where it needed to be. Did a compression check and it reads 75 psi. Now before you say this is low, please be sure of what youre saying haha, because some say it should be over 100 and yes, it seems low, but the manual claims 60-90 psi is reasonable I guess? (according to another forum). Oil level is where it needs to be, and coolant is full. SO.... what the heck, why wont it start! Ive heard of the cams on these getting the lobes worn down too much or something? maybe thats it? but i figured if i set valves properly it should be fine. I also dumped fuel straight into cylinder, no luck, as well as starting fluid into intake, no luck, which leads me to think its something timing or cam related but everything seems fine? what do you guys think. thanks in advance!