But it turns out our problem was the ignition switch (Polaris part # 4012165). This same part is used in many Rzrs over many years. It is a piece of cr*p in my opinion because it is all plastic and tends to fall apart especially in hot weather. The top part of the switch snaps into the bottom part but the little plastic nubs on the top part that snap into the bottom part tend to come loose because the bottom part is not strong enough to hold the nubs in place. When the top part of the switch starts to come loose, the connections inside no longer make reliable contact and you get intermittent hard starting.
Finally I read a post by MC Racer who had his rig fail to start during a race, engine cranked but no start, but it eventually started and ran fine. Hmmm…. so I removed the switch and sure enough it was starting to fall apart, 2 of the nubs were loose and the top of the switch was raised up enough to cause poor connections inside the switch.
Replaced the switch and problem was instantly solved. Plus the Rzr now accelerates harder, cleaner, faster. There had been some hesitation during hard acceleration that I must have gotten used to because it did not bother me, did not happen all the time so I guess I assumed it was just not warmed up or something. Anyway the Rzr now starts immediately and runs great.
But I do note that the new switch is also a piece of cr#p. This switch is bound to come apart again because the bottom part is not strong enough to hold the top in place, especially when the plastic gets soft in hot weather (and it gets hot here in Phx, AZ). So I am going to put a hose clamp around the body of the switch which will hold the nubs in place and absolutely prevent the switch from coming apart. I need a clamp that opens up to 1.75″….. just ordered some from Amazon. Meantime I put a wire tie around the switch which will hold for a while until I get the hose clamp.
So if you have hard starting issues, might be good to check the ignition switch, it is real easy to remove at least on our S 900. Simply remove front hood, remove two screws holding the center dash piece (Speedo, ignition switch, etc), pull the center dash piece toward driver seat, lift up and you can see and hold the ignition switch while turning the threaded retainer ring on the switch (the ring is also plastic so take it easy). Best to hold the switch with one hand and turn wrench with the other hand so the switch does not spin on you. There is another plastic nub that is supposed to stop the switch from spinning but the mounting hole is too big and the nub too small to work
properly so be careful. Anyway removing/replacing the switch is easy and fast, 5 min at most so it is worth checking.