My clutch started to crack also, but nothing like the photo. I checked out Yamaha and it was expensive. I ended up buying a Polaris for it... www.hartmaninc is were I bought it. He also setup the weights and spring.
I also recomend the Poo set-up from Hartman. After rebuilding several Yami clutch's I finaly listened to Tom about the clutch. I gave him a bad time for not being a better salesman and convincing me years ago...LOL