Hey, I'm feeling kind of lazy so I wrote this for a guy with a 600 but did the process on my 700. To get in the ball park of jetting look up the jetting chart of a 700XC.
It is pretty straight forward process, first the air lines that were running from the carbs to the ACCS need be rerouted into the air box (you can either drill two holes and silicon them in place or by some type of hose connector that fits the hose and drill the holes and put those on the inside with the nipples coming out and hook the hoses up. A 90 degree works good because there is no way it can come out of the air box from the inside. The whole point of this is so that the carbs are getting atmospheric pressure like systems without ACCS always do and the only reason you need to run it into the air box is to protect it from snow and derby (DO NOT JUST PLUG THE HOLE IN THE CARB OR CRIMP THE HOSE). From their you just need to figure out proper jetting which all depends on you altitude. If the previous owner never changed jets then the sled will be running super rich, the whole point of a ACCS is that you can put super big jets in it (I think mine had 185 mains) and the ACCS lowers the atmospheric pressure in the carbs so even with a huge jet it draws less fuel. The jetting will take a while (I was changing it out in the snow and it took about 6 or 7 tries). To get a general ball park either look up or call a polaris dealership and ask them what size jets they would run in 600 xc at your altitude. It has the same engine but no ACCS. That will get you close, I bought the size the XC is spec'd at and 2 sizes bigger and 2 sizes smaller for mains. The pilot should be either the same as the XC or one sizes bigger or smaller. Also I moved the clip on my needle to 2nd from the top (Only because I ride at 8,000 to 10,000 feet). That should get you close but it will take some testing to get it perfect. If you are changing jets while out testing then I would highly recommend using the filter from the air box as a parts holder while taking everything apart. There are a lot of small parts to lose. Also when you go get jets also pick up at least 2 of the E-clips for the needle (They tend to fly off when you take them off if you don't have them gripped tight.
As for testing the easiest way to see where you are at is to read plugs so I'll give you a quick run through on that too just incase. What you are going to want to do is give it a little less then 25% throttle while riding and hit the kill switch while going at less then 25% (This will check your pilot jet). After killing it pull one of the plugs and look at the tip, If it is black/wet then your pilot is rich and needs go down, If it is brown you are perfect and if it is white it is lean and needs a bigger pilot. Then put the plug back in start it up and repeat the process except this time kill it between 25-75% throttle, read the plug the same way as I just described and that will tell you how your needle position is, If it is black (rich) then move the clip up on the needle, if it is brown leave it where it is and if the plug is white move the clip down on the needle. Finally repeat the same process at 75-100% throttle (You don't have to 100mph just pin it until it hits full rpm's and hit the kill switch). This will tell you about your main jets same as pilots if black you need a smaller main if brown you are good and white you need a bigger main.
I hope that helps you out it is kind of a pain to get it figured out but mine runs 10x better now then it ever did with the ACCS on. If you have any question shoot me a message, I know this was a long message so if any of it doesn't make sense let me know and I will clarify.
Best of Luck,
-Evan
P.s. if you are still having issues I would look at the drive clutch and make sure the rollers roll easily and don't have any flat spots. If you let me know what exsacly it is doing I can probably help narrow it down for you and if you need pics of what I'm talking about I have the sled in my garage and send you some.
