Came across this little descripton on a USA bike forum.
I'm helping a friend revive a couple vintage machines. Unfortunately both are going to be street mules for now. The CB350 was a runner until two years ago, it apparently got real noisy, and then died with a bang. Upon teardown we determined the noise was the cam chain stretching beyond the point where the tensioner could keep it in check, allowing it to eat half of the front slipper. Fortunately, it didn't get into the cam chain galley at all. The terminal loud bang was the cam splitting, just past the sprocket on the points side. Sounds very similar to your blow up and the other cams that have snapped!
Hi Guys, I have had cam chain problems over an 18 month period i have broken 4 brand new D.I.D hyvo chains in my 1100 honda. Very expensive! spent a fortune getting things checked and measured, Only to find out the chain witch i understood was made in japan has moved there operations to china. when you compare a standard honda chain to the D.I.D chain the standard looks so much stronger.I hope my problems are over. Cheers David