Re: gas tanks..
.19 is a little too small for a bicycle engine. I wouldnt go any less than .25 gal. With a chinese HT engine, that will get you around 35 miles. I get around 70-75 miles out of 1/2 gallon.
In riding my bike, I find that 20-30 miles go past before I know it. I have run my 1/2 gallon tank out a few times by mistake because I'm enjoying riding and dont realize just how far Ive travelled since last fill. Luckily the few times I ran out I was within a mile of home and managed to make it back home easily.