The 83 is alive, but the shock.. WTH is up with the shock?

I got one of my 83's running today. Totally disassembled the carbs and cleaned this week, now today I got them reassembled, did a valve check (all 16 were tight), replaced coolant, put in new plugs and a battery, and it pretty much fired right up. Been sitting since 05 I believe. Ran smoky for a while, blew a bit of a mouse nest out one pipe, but within a few minutes it was running like a clock! Very happy to see/hear it.

Now.. I noticed the shock. When you compress it packs down. Bounce on it and you'll go down, then slowly, like over 20 seconds, come back up. This is just the opposite of what I'd expect of a sacked shock. I'd expect it to have no damping, not have uber rebound damping??? I put 20psi in it, and it holds air. Started wondering if the swingarm was nearly stuck, so I pulled the bottom shock mount, and the swing arm is free and smooth.

What do we think?

 

Shocking

Since the bike was in storage, The shock has probably not moved, this can cause the seals inside to dry out. The slow rebound should go away if the shock is healthy. Unload the bike with a jack , load , do this several time( no air in the shock), This should fix it, if not you need to obtain a replacement. my2cents.

 

Do any newer shocks interchange? I see some gen 2 shocks on ebay and they have the same wide clevis on the lower end, but I have no clue about the dimensions.

Or would a VF1000F/R shock fit? I assume a VF700F 84/85 is identical.