Thought I'd post this for others to reference.
In picture you see the differences in length of the '80 and '81 CB650C and Standard Models.
'81 Models are Air Forks
'80 Models are non-air forks
All should be direct swaps except for the '81 Custom model since it is a Dual Disk Setup. However, keep in mind that you will have to use the Front Fender that pairs with the forks due to bracket height differences.
I haven't checked the caliper brackets yet so I can't confirm whether the calipers are interchangeable. I'll try and compare in a couple days.
Especially helpful if you are ebay shopping for new forks or shorter/longer forks. Personally i'm going to use the '81 Standard Air Forks as they are the shortest of the bunch and are already configured for the Air assist.
Cheers, Joe
