quick question that i haven't gotten around to asking here yet: since i got this bike running (76 cb200t), i've noticed that after going 60-70 miles on a full tank of gas, the bike shows all the signs of running out of gas (sputters and loses power, regains smoothness and power for a few more miles once the fuel valve is switched to "reserve," then sputters and eventually stalls). but each time, i've only used about a gallon and a half, and there's almost another whole gallon sitting in the tank. it had the original fuel valve when i bought it and i initially had only cleaned it up and made sure all the passage ways were clean and clear. then i tried changing it out--put in a NOS honda fuel valve. same issue. any thoughts on this??