Si Mayeux

I fixed my Kawasaki Prairie 650 by installing a new head assembly and lo and behold, it broke a valve again and destroyed the piston.  I am concerned that the cam are causing this only on the rear cylinder.  I need some guidance on this and would appreciate all of your thoughts on this.   Si.

I am retired and am 65 yrs old.  Barely making a living and am having a problem with my 2002 Kawasaki Prairie 650 4x4.  It keeps breaking a valve and the end drops in the cylinder ruining my piston... I love to work on small engines and this is one headache for me and will accept all your comments on this as to helping me find what is causing this.