expected mpgs for a 1978 suzuki gs550e

[tkent02]

Another factor is that the smaller engines are designed to work better at high RPM, more so than the bigger bikes. Intake ports, cam overlap, carb and valve diameters, exhaust back pressure, combustion chamber size and shape, and a hundred other engineering parameters are all optimised to make power at high RPM, as that's what it takes to get positive press in the cyle magazines. A 550 designed from the ground up for economy might get 90 mpg, but it wouldn't matter, they would never have sold any.

[1948man]

Wait, huh!?! First off, lets say that your not getting "tire size miscalculations" as stated above. You really have to be accurate on mileage to gallons.

1. Fill the tank to the bottom of the inner lip.
2. Ride it for however long, lets say 112.3 miles when you pull back into the gas station.
3. Fill it back to the inner lip of the fill hole.
4. take the EXACT amount of fuel you put in, and divide the EXACT number of miles you rode (ie. 112.3 divided by 2.76 gallons).
5. THAT number is how many miles your getting per gallon.

Like stated above .10 of a gallon can change that number by 3-4 mpg...
So if you put 3.86 gallons and just divide it as 4 gallons it will throw you calculations down quite a bit.

What he said.