just found a site with a odd mix of bike sounds, was surprised to find sounds from my teenagerhood of being on two-strokes:
a single two-stroke enduro (this is a 100cc, I had a Kawasaki 175 but it has the same sloppy piston sound, takes me back to being 17...)
http://www.totalmotorcycle.com/Sound...ound%20clip.au
Yammy RD 350LC (says its a 1980, which was the last year of the aircooled ones, the luiquid cooled ones came out in '81--anyway,sounds close enough)
http://www.totalmotorcycle.com/Sound...und%20clip.wav
for those old enough, check out the '79 Honda CBX six cylinder--it was a beautiful and techno snazzy bike at the time, nice sound too.
and even a '74 GT750 triple two-stroker,
wish they had a KH400 (triple aircooled two stroker, a real screamer)
plus they have newer stuff....