And here is a bit more old school. I have several more to post...but first have to get the pics on photobucket.
This one is a 1972 Penton Berkshire 100 that belongs to a friend of mine. His dad was the original owner - bought it new in 1972 - still has the original sales receipt! This is the very bike my buddy learned to ride on when he was a kid. Full restoration was done in 2011.
close up of engine: