I think its a 520. Just wanna be safe.

 

To me it doesnt look like it. Seems like your still making good contact. Maybe lube it up a bit.

 

ya it still looks good......why did you want to change the gearing

 

looks like a good sprocket to me, can't tell if it is 520 but it has 40 teeth.

 

It looks fine.Is it tearing up your chain?If not than your good to go.By the way if you change the sprocket you need to change the chain also.Once a sprocket has been running for a while it and the chain develope a wear pattern.If you run an old chain with a new sprocket it will chew the sprocket up and vice versa with a new chain and old sprocket.