You need a 12 volt to 9volt voltage regulator. *The new bikes have an anti theft device (the PINK wire) in the stock ignition that kills both spark and fuel. *Put the voltage regulator between the hot wire in the ignition and the pink wire and then ground the regulator (there are 3 wires red, pink and black) and you're done. *I can't remember the part number but I googled it and I think it is a LM7809
here's the link for one:
http://www.surplustronics.co.nz/shop/pr ... S0508.html
P.S. *He sold you a line of BS if he said he got it running without the stock ignition...