Repro rubber seems to suck!
I tested Cruzinimage carb boots for K1-K6, deep cracks after a few months, first summer.
All rubbers inside engine sucks too if not Honda. Even battery strap cracked quickly. Honda last much longer.
The Honda K1-K6 boots were better in the 80's. They seems to be softer and thinner today. Old types replaced because they were hard, not due to cracks as the later gets after a few years.
I'm sure this is the same problem for the later bikes too.