Both Rob & Mike are right about Yoshimura. Especially in roadracing circles their parts were the go-to fast goodies. With this engine Pops seemed to like to do more with less in terms of displacement. Once guys strayed to bigger bores things went boom. Yoshimura was about lightweight components for high reving engines.
In the shop where I worked my boss roadraced and had these same rod issues when the bore went to 900cc. No-one liked blowing engines and he went back to smaller bores (preferred 810) and was very succesful. He was eventually thankful for RC rods that seemed to hold together. Let's be honest though in those days privateer mechanics were on their own and didn't have internet forums to access good information. So some ideas worked, some did not.
Cut to nearly forty years later....we have among other things, rods and pistons & rings available that are light years better than what was at our disposal then. Not to ruffle feathers, but I too am surprised at the renewed interest in old tech parts. Myself included, to still be playing with these old tech bikes descibes what we're about as individuals I suppose, nostalgia be damned!