These carbed ROTAX engines flood when you roll them over, sure you can pull like a banshee and it will start eventually, or, just chill for a few min, stop panting and overheating yourself, look around your at the fantastic area you are riding in, drink some water, by the time all of that is done give it a yank or two with the throttle pinned and it should start right up. You can also pull the plugs (like you did) and pull it a few times to dry things out if you really need to get going.
Another thing, check your jetting as unless the previous owner re-jetted it (down) then it's probably running rich anyway.
The aftermarket air filters and reeds shouldn't affect flooding while rolling the sled to unstick it, they will affect airflow to the engine and air/fuel mix so if the previous owner did those upgrades then he (hopefully) adjusted the jetting to match his work but it's easy to check and a very good thing to do. Search on here or on Dootalk on "throttle chop test" and also on how to read plugs and "jetting", below is a good link on plug reading, take it from there.
www.dansmc.com/spark_plugs/spark_plugs_catalog.html
Basically on a Throttle chop test you ride the sled for a bit (until it's good and warmed up), then you find a good straightaway where you can pin the throttle all the way to the bars for at least a hundred yards, a quarter mile is better and slightly uphill ir in a bit of pow is best, repeat that a couple of times and then on the third run or so hit the kill button with the throttle still wide open and ride it to a stop holding the throttle wide open. After that, pull the plugs and read them according to this link and that will tell you if you are running rich or lean and if you need to change your main jets. You can also read up on reading piston wash if you want to.
Doing this may not help much with your flooded sled after a roll over but it will help your sled run better and if you are running real rich then you are starting with oil fouled plugs, then flooding them more, then trying to start a real gunked up mess in there.
Best of luck.
