I have a 2003 sportsman 700 twin and upon take off there is a loud snap/clunk noise...almost like someting is being loaded up....the same noise occurs when braking hard down hill especially with the rear brakes on.....what could this be....doesnt sound to serious but I dont think its normal....any thoughts...also how full do you fill the trans fluid and the front diff....  

have you checked the chain to be sure it is tight enough or that it isn't too tight if you have adjusted it recently.  

there is no chain...its the style that has a seperate rear diff from the trans....front and rear are shaft drive....no chain here...  

oh gotcha.
so many models it's hard to remember them all by rote sometimes.

check the universal joints in the driveshafts'

Polaris suggests a quart of transmission fluid to fill it.
but you need to use the expensive polaris synthetic fluid.