John would be a verifiable source in my book.
Wost case scenario be would be an identifyable source with a current international profile and a reputation as an engine builder and parts manufacturer.
I hope the 336 china scrap story is and urban myth but I'd be listening to what John has to say
"THEY ARE MADE IN CHINA AND THEY ARE ALL SCRAP. THE LOBES ON THE RIGHT HAND CYLINDER HAVE BEEN MISGROUND AND WRECK THE FOLLOWERS"
At face value he has identified the problem on more than a single instance. Sure I'd like more info but I'm not going to ignore this advice.
My bike is slow but the earth is patient.