4 banger vs twins
 

If twins offer greater low end torque than their 4 banger cousin, being more street friendly would they get better mpg? I'm looking at the early 2000s suzuki gs 550 parallel twin vs bandit 650 4 banger vs the sv650 v twin. Ideally id like a 500 or 550 but seems to be a rare find to get a decent one some kid hasn't pimped out. Or, would a high horsepower 650-4 not need to work at low rpm and not matter anyways?

My last 2 bikes were a suzuki dr200 and dr650, the 200 one sipped fuel to the point of being ridiculous and the other got 5L/100km which is somewhere over 45 mpg

My 89 GS 500 e was good for a little over 60 mpg.

regards
mech

On all my bikes, more cylinders = less fe.

When riding efficiently, I got the same mileage on my 2001 ZX6R Ninja (carbed inline 4, ~100hp) as my current Ninja 650R (EFI inline twin, ~65hp). Both get about 50-55mpg.

When not riding efficiently, the ZX6R would get ~35mpg vs 45mpg for the 650R.

I also had a Suzuki Katana 600 (also a carbed inline 4) that got about the same mileage as the 650R.

I think there are too many other variables with motorcycles to worry too much about the number of cylinders for fuel economy reasons.

Bought an 07 gs 500f nakedised bike. 13000 miles. Stock exhaust big selling feature. I think a bigger front sprocket might be in order at some point

My GS 500E has been off the road for over a year since I got my GZ250.

regards
mech

1981 Suzuki GS1100 54 mpg cruising hwy (aftermarket racing fairing) 70mph. Got better mpg than my brothers 1980 Kawasaki 550.

Sure the rider and gearing play an important role on that matter, but a 2-cyl is still a more sensible option regarding fuel-savings compared to a 4-cyl.

The biggest efficiency factor is compression ratio, the higher the better from a thermodynamic perspective. Next is the rate of flow of air/fuel mixture as in cc/min. A longer stroke, under square, tends to have more torque due in part to crank offset. Most 4 bangers are designed to get their power at high rpm so stroke and piston mass are kept minimal. Compare this to an industrial engine. Reduced aero drag and weight means less power is required so less fuel is burned. So build a full fairing, maybe lose a few pounds, and consider converting your ride to diesel power or a turbo system.

At a certain point, pumping losses start to offset the benefits of a high compression ratio.