You should be cruising around at 3,000 rpm. At that low of an rpm it dont matter what you do to the bike. At what speed are you going and what gear are you in?

 

Those plugs look normal to me. Honda45's plugs look rich by comparison.

I do agree you can change plug coloring with a few short runs (with the enrichner on or lots of low speed driving) and I suggested he replace and re-check.

 

While I agree that 1,800 RPM is a bit low, there's no need to sit at 3,000 all day. These bikes run just fine between 2,100 and 2,500 RPM when you're just loafing along in town.

Mine will happily run all day long at 55 mph in 5th (~2,400/2,500 RPM).

 

I concur. But if you want or need to get up and go you will need to down shift. I am in 4th till a minimum 50 and mostly 55 on my 883. That's cruising speed and gear. 883 or 1200 will be a slug rolling into the throttle hard at that rpm.

 

Yup, you'll want to downshift to accelerate fast. But that's sort of the entire point of having a transmission - so you can cruise in a higher gear to save fuel and then downshift if you need to get up and go.

 

I have actually noticed better mileage when the RPMs are higher. At least on an 883 the motor works less at the higher rpm to keep it moving.

 

The best mileage is always at low RPM (usually around 2,200, but there's variance from engine to engine) at between 70% to 80% throttle. That's where all engines have their best brake specific fuel consumption (i.e. the lowest amount of fuel used per horsepower developed). In theory, the best efficiency would be at lower RPM with 100% throttle, but in practice both carbs and EFI run richer at 100% load which causes increased fuel use so that's why 70% to 80% is better in the real world. Racing engines are generally tuned for the best BSFC at higher RPM because they have top operate at high RPM most of the time.

Lots and lots of people swear that they get better mileage at higher RPM, but instrumented testing always shows better mileage by shifting early. This is because there's not enough engine load at higher RPM in the lower gears when just cruising to get into the good parts of the BSFC curve.

For more detailed information about brake specific fuel consumption than the introductory link above:
http://takemebeyondthehorizon.wordpr...sumption-bsfc/
http://www.circletrack.com/enginetec...l_consumption/
http://www.autospeed.com/cms/article.html?&A=112611

 

I ended up talking to keith at fuel moto and he added fuel in that 1800-2100 range and now there is no more miss . which i tried doing myself but i didnt add enough fuel to the program to make much of a difference i guess . i agree 1800-2100 is to low of a RPM but when im in town and trying to keep the pipes quite so the cops dont look my way ill chug it around that range

 

THat is some gnarley chit right there. Awesome reads. I just did some math. The 70% throttle number gave proved to be true to my amazement. I just got learned something. I get my best mileage right at 4,000 rpm in 5th thats 340 rpm less than your 70% number. I am going 71~ at that rpm. When I cruise at lower speeds of 55-60 or 3400 rpm for 60 mph I get a few less mpg.

I am going to read up more on that. I always wondered why on the highway I got better mileage going 70ish than cruising around at 60.

But at lower speeds in the city I still notice better mileage if I keep it at around 3,000 RPMs. So thats what I cruise around in while in city traffic.

Thanks for the info.

 

Agreed - thanks for the info/math. I've noticed the same thing (higher mileage if I'm a bit on it vice otherwise).

I also tend to keep the RPMs higher.....bike runs better for me and has more immediate response. Don't shift out of 4th until 65 or so at this point....really takes being on the highway to get into 5th gear for me.

Last fill up I got right at 52-53 mpg as well - win, win.