Had one of those (still in the shed), they're bloody fantastic to whizz along touching 40 (just).
Watch out for the fuel tanks, i went through 3 of the buggers before i realised the way they make 'em with the crappy welding on the threaded studs means that they will always start leaking after less than 50 miles, however that could have been because my particular one was so vibratey that it could shake the tits off of Pamela Anderson. My mates one was smooth as a normal moped and i think that allowed it to go faster, maybe his engine was slightly better balanced.
Getting pulled over riding it is why i now stick to driving a car instead, the look on the coppers face was worth it though.
Oh and i used to replace brake pads every 20 miles, but that was probably because i was too cheap to buy anything more than a £4 set of pads.
Edit: Another thing to remember is that motorists don't expect you to be doing 40 if you're not pedaling! Me and my mate used to get cars pulling out in front of us at junctions because they would misjudge our speed.