How do I take my chain off or adjust it on my DS 650 to put a new sprocket on or other adjustments like that?

depending on the sprokets you get you may have to get a longer chain or shorten it. Its a good idea if you change any of the sprokets after any long term use that you change the chain out too so that everything wears evenly.

To adjust the chain....
1. Look in the owners manual and it will give step by step instructions.
2. On the side of the rear sproket fingers you will notice a hole. In your tool bag there is metal rod. Place the rod in the hole and roll the quad while applying pressure to the rod. When the rod gets close to the bottom of the swing arm it will slide into a hole in the eccentric. Loosen the 2 bolts on the end of the swing arm. With the bolts loose and the rod in the sproket finger you can then roll the quad forward or backward to aquire the proper chain tension. I believe there should be a little less than 1/2 inch of slack in the chain. Make sure that once you have tightened the bolts down that you get on the quad and bounce it up and down a few times and make sure you are not to tight when under load. You can tear up the rear bearings and a multitude of other things. I remember seeing something in the book about adjusting the chain while there is the weight of the rider on the quad. You might want to have another person around to help or you can use sand bags, weights or anything to add you weight to the quad.