An excerpt from my R90 thread, when I got the bike: "I hooked it up to a battery charger, and got the starter button to work finally. But, I heard crackcrackcrackcrackcrack when I press it. Hmm.. did it seize up? I am pretty sure I could turn 'er over with the kick start. So, I try the kick start. It's not going ANYWHERE. Damn it. So, I pull the clutch and try the starter button. Now it's just bogging down instead of crackalacking. It's still not turning over. So, I pull the clutch and the kickstarter can swing down now, too.. but that doesn't turn it over, and there's little-to-no recoil. Damn."
My engine was seized and I had transmission issues.
I doubt your problem is anywhere near as severe... unless you've left your bike in the elements for 25 years, too.