I'm order a new chain and sprocket set I was thinking of going for a 520 x-ring chain with 14t on front and a 40t rear alloy sprocket. Would this be a good set up? I still want the bike to do 120mph+ also I I was thinking is there anything to worry about with a 520 chain as the standard is 525? Thanks

Yeah that's my preferred combo, it will still hit 120.

Just remember that any gearing changes will throw your speedo out. Depends how much you use the speedo as to whether this is an issue for you.

Ok great thank for the help, I only really look at the speedo for speed cameras lol