DO NOT MIX 530 and 520... use the old 530 till you can get the incorrect rear swapped for the correct unit...

besides.. that rear doesn't look too bad.. some cupping on the tooth but over all it will be fine until you have the correct unit.

520 and 530 don't mix.

Yea looking at the width of each rear sprocket I thought...there is no way the Vortex 520 can be safe. I figured it would be much harder on the chain from a smaller contact area an the chain moving from side to side than my old one would be.

The manufacturer label says 520 but the motosport label/barcode says 530 so someone screwed up in the inventory.

Fortunately the old sprockets didnt look too bad, they were both Sunstar. The old chain was a Bikemaster, it actually held up for quite a while. Ive put almost 13k miles on the set. About two days before I ordered the new chain an sprockets it started clicking as I rode an could feel it in the left foot peg. I looked it over an found 2 pretty stiff links but when I went out an cut it off today I found this..


and this on the other side of the same link...

when I cut the link the side fell out with half the pin an I pulled the other side an half out. Roller sleeve was still intact but clearly worn. Funny how a pin snaps on one side an the sleeve wears thru on the other.