Is there any way to change second gear without having to split the cases on a 1982 Yamaha venture royal xvz1200 thankx?

I'm afraid not.

I'm in the middle of such an operation myself, and it's really not as bad as I thought it would be. But you do need to have some mechanical savey and keep track of the whys and wherefores to get it all back together because there are a s...t load of parts in this thing!