I use 428 sprockets with #40 chain. It's much lighter and rolls very easy. I've never had an issue w/it. It so cheap that you just throw another chain on every now and then. It has 1/2 links.
Available at any tractor supply or go-kart shop.
Your gearing is 10/22 for 520
For 428, stock is 12/26
I wouldn't think much gearing change would be needed for the dunes but possibly a 13 front.I'd have both the 12 and 13 on hand.
2000 GNC 5N\
2001 GNC 9N \ 40+ class
2004 GNC 9N /
2014 rock crusher "GO tortoise GO!"
2016 Byrd Rooster
Father of the "11" time National champion,and worlds fastest woman ATV racer
A few fast LT80's
250R~300cc's
300ex
350 Rancher
Kymco Mongoose
Survivor of the 12 Hours of ATV America 04 and 05