re. buying a motorcycle in Iran
Another belated reply, but for the sake of extra info . . .
I was in Iran for 5mths in 2007 and looked into buying an Iranian 125cc.
Prices were roughly equiv £300 for a new bike with option to sell-back - the usual Chinese rip-off of Yamaha model though would do the job - though I went off the idea since the fuel ration came in.
While in Lorestan province, however, having discovered a way around the
fuel ration (I think the ration was quartely, though could be used up in a
week if you so chose) I sold the bicycle I had resorted to riding - which was killing me - and bought a second hand motorbike for c£100. I was punching the air with joy as I rode out of town for the hills . . . right up until the police caught up with me a day later and promptly made me sell it back to the super guy who had sold it to me. Apparently foreigners are not allowed to buy Iranian bikes, though I wasn't sure if they made that up just for me, since the authorities seem to assume travellers off the beaten track are spies. Anyway, it was an amusing adventure involving several arrests and thumb prints, though all done with impeccable Persian etiquette.
So, as the other threads state, take your own bike in with a carnet. No cc limit and have a wonderful time in a fascinating country.