If you have a welder this is not lickly the best fix, for everone elce...
My kick start lever was rotating too far around and my foot would slide off easily.
A few people sugjested a little weld build up on the part that gets worn down causing the problem. I just taped a small 4mm hole about 4 threads deep. I then screwed in a 4mm bolt and grinded the head down to an apropriate amount (leaving enough to get the bolt back out). That becomes the stoper. I will post pics as soon as I get my camera back. May not last forever but its woorking good now!
I anticipate the kicker will start to mash over the bolt, but it should last for a few years.