DO YOU GET 100 km PER 1.2 litre fuel WITH A 48CC ZBOX MOTOR KIT

DO YOU GET 100 km PER 1.2 litre fuel WITH A 48CC ZBOX MOTOR KIT??
I FILL UP MY 2 LITRE TANK AND IT DOES NOT GET NEAR 100KM
HOW DO YOU GET THE MOST OUT OF YOUR FUEL?? E.G.DO YOU GO FAST OR SLOW? e.g

I'm dying to try this winter and I'm eager to hear what the wizards here on the site think.

Neither of the guys here at work have come close but they've both retrofitted cheap, heavy, Walmart quality steel bikes with 70-80cc's. They're both big guys too, 200+ lbs. plus 60-70 lbs. of motorized bike. I'll be retrofitting a much higher end bike with a 48cc and a disc brake mount sprocket. If I can't get it at 150 lbs. plus 50 lbs. of motorized bike, I'm not sure it can be easily accomplished.

let me tell you about the fish i caught, it must have been ----. first liar never has a chance.