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Discussion Starter · #1 · (Edited)
I've been tracking my MPG pretty religously on Fuelly. It's been very satisfying see my MPG staying in the low to high 70s range. My only complain is that Fuelly doesn't provide any good graphs for comparison/analysis. So being data geek, I plugged all the numbers into Excel and whipped these up. Pretty interesting.

PS. in add to mileage, fuel consumption, I also track temperate and commute condition in a separate log.

The result is pretty self explanatory:

1) I've noticed that the colder it is (damp cold winter in Seattle), the more fuel it consumes to push thru the denser air.

2) The more city riding I do (below 40 miles), the better mileage I get. I do accelerate mildly from the stop light, shifting at 5K RMP.
2.1) There seem to be an anomaly - my initial tank after taking her home got exceptionally good mileage. I think the dealer overfilled the tank. I tried to fill it up to the same level each time to make sure it's consistent.



I will continue to track and plot more graphs going forward. ALso looking forward to warmer condition to see if better MPG can be achieved.

Cheers,
 

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Great info :)
You may want to plot different shift points (5,000 RPM, 6,000 RPM, 7,000 RPM) in your city commute for an entire tank vs mileage obtained (MPG) to find the most efficient shift point (RPM) for the 250cc single. That would be useful info for anyone trying to squeeze out the most efficient performance for the CBR250R.
I want to do a run at a constant 45 MPH in 6th gear for 100 miles and see if I can burn less than 1 gallon of gas. Just need to find the right place to do it with minimal stops (the hard part).
 

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how'd you manage to get so high?

i average around 60ish recently
the city driving was killing my MPG, the constant stop/sart of the traffic lights was madness...

i do only ride 7-8 miles to work though, literally get on the freeway at my house and get off at my work
 

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Discussion Starter · #5 ·
You may want to plot different shift points (5,000 RPM, 6,000 RPM, 7,000 RPM) in your city commute for an entire tank vs mileage obtained (MPG) to find the most efficient shift point (RPM) for the 250cc single. That would be useful info for anyone trying to squeeze out the most efficient performance for the CBR250R.
I think steady gradual acceleration and shifting by 5000 RMP is more than enough. Revving higher than that just burns more fuel. In city ridin, I also try to use as little brake as possible. Any time I use brake, I am wasting potential energy. So I coast with clutch in to slow down. I also use engine brake. I also try to stay as close to 40 mph as possible and stay in as high of gear as it allows

I want to do a run at a constant 45 MPH in 6th gear for 100 miles and see if I can burn less than 1 gallon of gas. Just need to find the right place to do it with minimal stops (the hard part).
That would be really interesting to do. I am tempted to commute the same way as usual, except when I am on the hwy, I would stay on the right lane and do 50mpg. Do that for a full tank (1 week's worth) and see what happens.
 

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Discussion Starter · #6 · (Edited)
odd..i have always heard you get slightly better gas mileage in colder weather..(something about the gasoline)
I heard the same thing, too (for cars). Colder and denser air goes into the engine and creat bigger combustion and power. I am not sure if that makes that big of a difference for a 250cc motorcycle. I would think aerodynamics plays a bigger part for motorcycle, especially on the hwy. Motorcycle, in general, has much higher drag than cars. So the denser air requires more power to push thru.

I would like more datapoints though. so far, I have 12 fill ups. The key, I think, is to be as consistent as I can and keep collecting data. That means I will have to resist speeding and twisting the trottle. :D
 

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I dont worry about gas millage. Dont really care I just enjoy riding the bike. Its great it does get good millage but I dont track it and never will.
 

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I'm not surprised to see better mileage in warmer weather.
It was explained to me once that colder and denser air will make the ecm fatten the air/fuel mix so you get more power but you're also consuming more fuel.

I don't really know if it's true or not but it sort of makes sense to me. I know vehicles generally have more power at sea level than they do at higher elevations due to air density so maybe the same is true with cold air.

I honestly don't know but I do know that my mileage has dropped a bit since winter began. I went from low 70's to high 60's and I haven't changed my riding habits.
I haven't seen anything at the gas pumps about 'winter blend' gas (live in an area that doesn't freeze much & never snows) but who knows what they do without bothering to inform the public.
 

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odd..i have always heard you get slightly better gas mileage in colder weather..(something about the gasoline)
Nope - it's the opposite.

Fuel blended for cold temps contains less energy than summer-blend fuel.

Cold air is more dense, and will make more power if addition fuel is added (F.I. will correct the mixture based on temp).

In cold temps you spend more time running rich at start-up, it takes more time to reach operating temp, and the lubricants (greases) are more viscous - creating more drag. Add to that, fuel with less energy and a richer mixture to compensate for the cold air and it all adds up to significantly less mileage.

Winter-blend begins in most areas as early as mid-Sept. It's noticeable.


Jay
 

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Nerds! So this is where my people hang out.:p

I don't have much empirical evidence, but I got better mileage as the weather cooled. Right now I get 65 mpg and I used to get around 56. I rev the bejesus out of her now, but I bet my shifting technique and aerodynamics are better because I keep my body leaned forward more than when I first started. Anecdotal evidence suggest that my engine has broken in and is running more efficiently. It just seems like we accelerate quicker and I used to feel she was a slouch after 60 mph, but now I'd say she gets a little lazy around 76 mph.

I wonder if my tendency to shift at a much higher RPM range (7-9k) is the reason the cold air seems to offer an improvement. It might be that I fear sliding more with the wet surface and don't get on the throttle or turn as aggressively. What about the humidity? There are too many variables that have been changing to know for sure. Interesting conversation for sure and I look forward to what we find out.
 

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Getting much better performance and response in cooler 20 degrees than the 40 degree temps, and i'd say economy would be similar.
 

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Getting much better performance and response in cooler 20 degrees than the 40 degree temps, and i'd say economy would be similar.
Performance - yes.

Mileage - not necessarily. How are you getting more performance? By burning more fuel.

Carbed and FI engines do not react the same to cold air. A carbed engine will run lean in cold conditions, so it may (or may not) get better mileage. A FI engine will automatically richen the mixture to compensate for the increased air density of the cold air.


Jay
 
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