Strange one I know... but so far i've been out on my PCX about 9 times, and on a few of those rides, where i've been on an A road and doing 50 - 60, after a while I get a smell that is exactly like popcorn! Doesn't happen when i'm just doing 30 around town... only seems to be when i've been going faster for a longer stretch (10 mins at 50 for example).
Haha fortunately not. I knew this was a bit of a weird one... But thought was worth an ask. Maybe some corn has gotten into the exhaust. I should put some butter and toffee in there too and see what delicious snack I come up with by the end of my ride
If the bike is new, it may just be the new plastics/rubbers that you're smelling when they get hot... such as when you've been riding at near top speed for an extended distance. I know my PCX used to emit some various odors when it was brand new...
If spark knocks or picking occours at a steady engine speed under normal load, change brands of petrol. If it persists, contact your local Honda dealer. This ifo is from the PCX manual page 29.