I have a 2002 Suzuki King Quad, bought brand new last month. It only has about 30 miles on it. The other day I was out riding a small mud area. After a couple of passes through the mud I heard a loud ratchetting sound from the rear axle area. I came off the throttle and it stopped. Thinking I was just hearing things, I kept riding and about 30 minutes later, heard it again. Both times I was in 2wd, high gear range, 2nd gear at about 1/4 throttle with the rear tire spinning in the mud. Both times the sound stopped when I let off the throttle. I took it to the dealer who looked to see if I had oil in it, then told me they probably would not be able to find the problem and would not be able to re-create the conditions (mud). They said since I still have 5 months left on the warranty, to keep riding it, if I keep hearing the sound or if whatever is making the sound actually breaks, they will replace it under warranty.
Any ideas on what would make or cause a sound like this? Any thoughts on what the dealer told me?

Try another dealer, if they tell you the same thing I would take it out to the mud hole and blow it up! Better they pay for the repair than you.

my .02 worth