Final Drive Sprockets

All.

I've upgraded my rear break to a conical style and while alot better than stock, the smallest toothed sprocket I found was 47 teeth. This is obviously making the bike geared a bit short, So i'll be chucking on a 21t front sprocket.

My question is, what else do I need, none of my manuals say anything about a seal/gasket between the inner primary around the sprocket?

Also looking at a belt drive kit. I know this has probably been extensively covered in the past but I was looking for an up to date recommendation. I've heard the Bob Newby system is excellent but at almost 500 pounds (~AU$1000) my wallet winces a little. . . . .

PS If i go a belt drive will it change the ratio between engine and gear box or are they made to the same as stock?

Steve Maney's belt drive kit gets rave reviews. I have one but haven't fitted it yet, the quality does look good.

And his kit raises the primary gearing by 10%. So you may not even need to change the sprocket ...

I'm not sure if maney does a 25mm kit for an atlas to be able to keep the alternator

I have the Newby set up on the 650ss and it is nice. The Newby kits are expensive because they all include a complete new dry clutch, whereas most of Commando kits use the old clutch.
I could never get the stock 650 clutch to hold. Even the New by kit had to have it's springs tightened a bit more than I would have liked.
Don't know what it is about that 650. Herb Becker tuned the intake ports "as I do for the racing Commandos" It hits a very strong power band at 4 k, which is when the old clutch would start to slip.

Glen