I to have a Cimatti city bike!! And I bought mine at a sale to. Sounds like not enough gas but to check just look at the fuel line. I had that problem and was air/vapour locked. soooooooo simple. Take off the line and flow the gas, to let spill a bit. then pit back on. May be that! Any idea how fast yours go? I can not get mine past 30 mph. I am working on getting an upgrade kit from 50cc-65-70cc. Steve's Moped in NewJersy has it coming soon! It will be about 190 bucks. But will give it at least 10-15 mph more!! Sound good? I can't wait. Put a fuel filter in your line as well. Can get one at a lawnmower shop/bike shop. easy to install. I am getting the signal light kit for mine from Steve's also. Expecting any day now! If you want to contact him you can do so at 1.201.384.7777
My name is Duane and can reach me at semmelvon@yahoo.com