Motorcycle Repair: 71 350CL cam chain, staking tool, sunday wife

Question
Hi Rich! My '71 Honda has 10,500 miles, and has been running great. I was out riding this past Sunday, wife on the back, when ZAP the engine died and spun slowly to a stop. No warning nor any unusual noises before or during. The cam chain had broken -- I suspected as much, and today pulled the top off the engine and confirmed, the chain was hanging loose over the top sprocket, the ends twisted and snapped apart.  I did not immediately see any collateral damage with the valves, but haven't taken it down further.  What might be the cause of the chain breaking like that? And, what is the basic procedure for replacing it; is there any way short of cracking the engine case apart and pulling the crankshaft?  Do you recommend the OEM chain, a Tsubaki "high performance" chain, or a chain that has a master link? Thanks, you da man!  Gary

Answer
Gary, to do the job right you have to break the engine down both top and bottom end because there's no other way to get the continuous chain around the crank.  However, you can a CB450 master link and break the chain and replace the link you removed with the 450 master link.  The only problem is that that link requires a staking tool to peen the ends of the link so it doesn't come apart. If it's not properly staked, you'll get to do this again.

I've never seen a chain break and I can't think of anything that would cause it except for wear.  Take a close look at the sprockets and make sure they aren't worn funny which could have accelerated the wear on the chain.  

Regards
Rich