Swingarm and tire Questions

How wide of a rear tire and wheel combo can I run on an 81 650? I have read some of the Fighter style build threads and I have noticed prople talking about offset sprokets. I understand what they are but what I dont understand is why I only hear about them on the bigger bikes, are they not made for the smaller cc bikes? I am just curious what my limitations are in this department. I plan on converting the bike to a mono shock. Thanks to anyone who can help!

When you swap the swingarm and use a wider rear rim/tire combo, the width of the tire will hit the chain.
You have to move out the chain at the front using an offset sprocket to compensate.
On the early 650s, '76~'80, you can go up to a 130 width tire on the back on the stock rim/arm set up, without needing an offset sprocket.
I'm not sure if a CSR will take a 130 tire though.
I've only had my CSR for a few weeks, so I'm going to be looking at what mods can and have been done by others.
You don't see many 650/CSRs with mods, other than bobber/chops.

My CSR has a 130 tire on it now, looking at it I could probably fit a 140 on it if I took the chaingaurd off. I have checked Z1 Enterprises and it looks like they only have offset sprockets for 1000cc bikes. Where can I find them for the 650's?