While following w/ interest the recent thread concerning the difficulty of
finding the correct size, and then, the gold plated  price of the fancy
neoprene breatherhose,  I  noticed that my breatherhose had collapsed.
Tried unsuccessfully to locate the correct size heater hose replacement at
7/8", or metric equivalent.  So, cut a 4.5" segment of .75"  (3/4") heater
hose and after reaming-out the inner surface of the old neoprene hose with a
short length of 3/4" copper water pipe (removal of old gunk helps provide
space for new gunk), inserted the 4.5 segment inside the middle of the
tired, collapsed original breatherhose.   Immediately changed the shape of
the hose into more what it originally might have been, i.e. round.
Incidentally, took the add oil cap off the spout afterward, while the engine
was running and could notice the difference.  Silicon lubricant was
essential.