yamabob - thanks for the PM directing me to this thread. I had the exact same noise with my bike. I am still not sure if it was an overtightend cam chain or bad cam bearings because my project got bigger. I didn't have any plastic pieces from the cam chain guide or tensioner in my oil filter, but I also didn't tension my cam chain with the engine hot.
I ended up dropping my engine and popping the top off and sliding off the cam bearings. These need replacement or at a minimum solvent cleaning. Rolling my bearings by hand wasn't rough, but had a lot of friction. I'm thinking they sat too long without running/getting oil.
There is plenty of advise on adjusting the cam chain tensioner with engine hot on this site. I'd try that first. If it doesn't work, replace the cam bearings. Thanks to advise I got here, I know it can be done without breaking the cam chain. If I didn't have more work to do with my engine, I would have had the engine out, bearings changed and engine back in over probably three to four hours.
BTW, nice bobber!