It's worth reviewing this article in the tech section of the Old Britts web site - http://www.oldbritts.com/o_ring.html. 

Additionally there was a thread on accessnorton - http://www.accessnorton.com/520-ring-chain-yea-nay-t6017.html - that MexicoMike summarizes like this:

"A 520 X ring chain conversion produces a CHAIN that wears much longer but it wears out the 520 sprockets much faster than a standard 530 chain wears out the oem 530 sprockets."

The way I understand it is you want X-ring not O-ring chain. O-rings need tighter clearances to seal, which makes it a stiffer chain. X-ring chain is more flexible which apparently is good as it tends to run better on the sprocket teeth. However, the real issue is the smaller contact area with the 520 chain which increases pressure on the teeth which increases wear.

So it seems if you're interested in long chain life and low maintenance, you go with the conversion. If you're more interested in long sprocket life you stick with the original 530 chain. 

I decided to go with the conversion as I'm  not much of an aggressive rider and since I never seem to have enough time - the lower maintenance was appealing. I guess I'll see how it goes.

There are three things to change

1. The countershaft sprocket - requires pulling off the primary chaincase
2. The chain
3. The rear drum - You'll to either have the teeth on drum turned down or purchase a modified drum. In my case I purchased a drum as my old one was worn and I didn't want to have the new chain run on a worn sprocket.

1 Changing the countershaft sprocket

According to the Workshop manual, in order to change the Countershaft Sprocket, you need to complete section C14 then proceed to Section D8. (You actually you need to start wtih C13, so...)

C13 - Removing Primary Chaincase

C14 - Dismantling Primary Transmission and Clutch

D8 - Countershaft (Gearbox Final Drive) Sprocket

Don't forget to check your clearence between the new 520 chain and your gearbox. As stated on the OldBritts site:

"The clearance between the countershaft sprocket and the gearbox shell is minimal at best and should be checked. I place the chain on the bike with the master link in place (the master link is a bit fatter than the rest of the chain) and spin the chain so the master link runs past the gearbox shell. If the master link did not rub against the shell, you are fine. If the master link did rub against the shell, you will have to shim out the sprocket. The only shims available to shim out the sprocket are (part # 06-7569, $2.05) and are .003" thick. The shim or shims will go in-between the counter shaft sprocket and the bearing spacer (04-0131).

The sleeve gear (4th gear main) fits up against the inner race of the mainshaft bearing on the inside of the gearbox and the bearing spacer fits up against the inner race on the outside. The shim or shims fit up against the bearing spacer and the countershaft sprocket fits up against the shims or the bearing spacer with the sprocket nut pulling everything together."

2. Replacing the chain

C41 - Chains - Rear Chain

3. Changing out the rear drum

H5 - Rear Hub Reassembly

Parts List