Umm... what? Heat engines run less efficient the faster they are running. They depend on heat transfer to produce power. An engine running slower will allow more time for the heat transfer to take place which equates to a more efficient engine. They produce more power and torque at higher rpms, but do it less efficient. If our engines ran most efficient at 11,000 than I would never leave 1st or 2nd gear and expect to get 50mpg.

 

so am i the only person getting 45+ mpg? i must be babying my bike more than i thought! i do tend to keep it under 8k rpm unless im passing someone and its mostly highway miles back and forth to work.

 

I get about 40-50 on my f4i depending how I ride. I get about 35 or so on my RR.

 

I'm sure I could get 50 mpg if I kept it at 65 on the highway. On a tank that's used mostly for commuting to work, I'm in the mid to high 40s, and that's rolling at 75 or 80 most of the way. Any riding that involves a lot of braking and accelerating, like track or twisties, or even just in town with stop signs, will be a lot lower.

 

You all have to remember something here. If your speedo is not 100% correct, your calculated fuel economy is going to be off as well.

 

But if the OP is -1/+2 then he should be putting more miles on the ODO than what he really is and therefore that should actually improve his gas mileage. I had a speedohealer on my F4i with a -1 front sprocket and it wasn't calibrated to perfection so I was 10% off the other direction so I was putting on 10% less miles than I actually was so that would "hurt" my calculated gas mileage because it said I wasn't going as far on a take of fuel.

 

I agree R Dub. I was talking to the people that think they are getting 45 or 50 MPG. I get a 100% accurate (SpeedoHealer) 36 highway and 32 city, I can't believe there could be that much of a difference between bikes! I guess weight might have something to do with it, but I am only 170 lbs.

 

You sir are incorrect. Engines peak efficiancy is the same point at which peak torque is made. This is a very VERY basic concept when it comes to internal combustion engines. Engines are least efficiant at idle and most efficiant when at 100% throttle [assuming you keep the a/f ratio exactly the same] so you would get max milage from an engine at 100% throttle and peak torque rpm. Of course thats not feasable in the real world.
As for leaving it in 1st or 2nd to get better milage, your basing everything off engine efficiancy and not taking a single other variable into account. Things like trans ratio, wind resistance, fricition from parts like bearings moving faster etc. You obviously are a smart enough person to be getting started on thermal dynamics but you need some more time with internal combustion and vehicles.

 

Heres something I copied for ya:

"Modern gasoline engines have an average efficiency of about 18% to 20% when used to power a car. In other words, of the total heat energy of gasoline, about 80% is ejected as heat from the exhaust, as mechanical sound energy, or consumed by the motor (friction, air turbulence, heat through the cylinder walls or cylinder head, and work used to turn engine equipment and appliances such as water and oil pumps and electrical generator), and only about 20% of the fuel energy moves the vehicle. At idle the efficiency is zero since no usable work is being drawn from the engine. At slow speed (i.e. low power output) the efficiency is much lower than average, due to a larger percentage of the available heat being absorbed by the metal parts of the engine, instead of being used to perform useful work. Gasoline engines also suffer efficiency losses at low throttle from the high turbulence and head loss when the incoming air must fight its way around the nearly-closed throttle; diesel engines do not suffer this loss because the incoming air is not throttled. Engine efficiency improves considerably at open road speeds; it peaks in most applications at around 75% of rated engine power, which is also the range of greatest engine torque (e.g. in the 2007 Ford Focus, maximum torque of 133 foot-pounds is obtained at 4,500 RPM, and maximum engine power of 136 brake horsepower (101 kW) is obtained at 6,000 RPM)."

 

I routinely check my odometer against the road's mile markers, and I am consistently either exactly on or maybe 1 or 2% low - after 10 miles according to the mileage markers, my odometer has moved 9.8 miles. So my mileage is real.

My old F3 was 4% high. Both bikes had stock gearing.