A VERY good topic.
Like the "back pressure" myth, I regularly hear that you cannot have good fuel consumption and best output... this is false. The problem is that most riders do not want to pay for the required dyno or road time required, and many "tuners" do not have a good grasp on what is required, and do not understand lean burn at low loads.
You can have mapping for very good fuel consumption at cruise, and best output everywhere else. This is often misunderstood by riders and some dyno operators alike.
With electronic engine management, you can have your cake and eat it too. It just takes a good understanding of engines, engine management, and taking some time to learn what is required.
Mapping for best output at low loads where cruise occurs can be self defeating on road bikes. Even on road race bikes, I have found that having a region that gets good fuel consumption when drafting behind another bike, can allow less fuel to be required on the track, and this means the bike can weigh less, accelerate a bit better, allow a bit later braking into turns, and be easier to toss around through corners on track. A gallon of gas weighs roughly 6.25 pounds, and in the tank, this weight is located fairly high on the bike - we do try to lower this on some bikes. Even F1 and NASCAR racers incorporate these same strategies.
If you are going to map a bike for higher mileage, a canned tune will not be the answer. There are simply too many differences bike to bike, and use to use, for a canned map to work as required for best fuel consumption across a range of bikes with the same engine design.
You also need to look at your bike and the speed where you cruise. Fairings, windscreens, bags, pile-ons, speeds, and even the angle of the exhaust tip(s) can play a part in fuel consumption at cruise. As can the roads you ride, and how you ride them.
Your brain and mental attitude/approach can play a part here. One recent example is a member here that claimed he had a "performance" map and an "economy" map. When I had him send me the maps, and looked them over, there was no difference in the mapping anywhere near where he cruised - NONE. He simply thought there was, and mentally approached his riding differently once he loaded in his "economy" map. This gave him a very noticeable increase in fuel consumption. It is a placebo effect. Strange, but true.
You might be amazed at just how lean you can run an engine at low loads without any issues. But your cooling system may work a little harder.
I regularly tune the region under 10% throttle opening fairly lean for good fuel consumption, with plenty of acceleration compensation, then tune the rest of the map for best output. Many riders claim 33-36mpg. I have mapped a couple of R3s to run well even leaner in this region, and these riders claim they are getting 40+ mpg at 75-80 mph cruise - even better when cruising slower. This is with aftermarket full exhaust systems and intake work that is intended for best output, not best fuel consumption. And these riders commonly ride in northern Alabama and eastern Tennessee, that are not known to be particularly flat. It would seem that there is room to go for even better fuel consumption.
I have yet to see just how far we can go with fuel consumption in the R3 as the main (or a major) priority, but it would make an interesting project. And likely one that would have to come out my own pocket. The dyno and road testing time required would be a bit daunting for many. The issue is...TIME! I need more time in the day, and more days in the week.
If you pay particular attention to fuel delivery so that it is atomized and homoginized well into the chamber (altered by injector patterns, their location/angle, and fuel pressure) you can get the engine to run even leaner - some cylinders will run leaner than others before lean misfire due to engine temps per cylinder, and a few other details. Then it will basically come down to the strength of the ignition system and how far you can go before lean misfire. I have been able to use high output CDI or inductive ignition systems on several bike engines to run very, very lean without misfire.
Exhaust gas recirculation, secondary air injection, and cam timing play a part here.
Compression ratio also affects cruise mileage considerably. The stock R3's low static compression ratio is not really a good starting point for pump fuels. I am working with a new piston source to cut costs roughly in half for R3 pistons. This might make it more attractive for more R3 owners, but I doubt it.
"Smokey" Yunick's hot vapor induction engine designs might be interesting to explore on a motorcycle. I have been kicking this around for several decades.
One obstacle you will face with the R3 getting good mileage at interstate speeds will be gearing. The R3 engine makes large amounts of low rpm torque - even at low throttle openings. With the engine speeds in 5th gear being what they are at 70-80 mph, the engine is turning more rpm than is really wanted or needed for out and out best fuel consumption. This large engine really should be geared so that it is just loafing along at interstate cruising speeds. And it is possible to have custom gears cut for 5th gear and the final drive. But the cost to do so, isn't exactly economical.
More than you asked, but I hope it helps,
-Wayne
on why would you want to do that comments that I see on here from the die hard go fastest R3 brothers. It might come in handy for those iron butt runs and of course even detuned for mileage you would still be out front do to the nature of this beast
