Fuel economy dropped to ~40 mpg - Honda CBR250R Forum : Honda CBR 250 Forums
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post #1 of 18 Old 12-19-2016, 03:45 AM Thread Starter
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Fuel economy dropped to ~40 mpg

My fuel economy sharply dropped from about 65 to about 42 after I moved earlier this year to a more congested area. My trips are shorter and have more traffic on average, but I did not expect the difference to be this drastic. Do you think the drop is just because I'm using the motorcycle differently or because there might be a mechanical problem?

I attached a graph of my recent fuel economy in miles per gallon. The drop aligns with when I moved. I was consistently about 60-65 mpg before.
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post #2 of 18 Old 12-19-2016, 05:30 AM
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Ye gods! Are you riding everywhere in first and second? Even accounting for the difference between US and UK measures (I assume you're US?) that's terrible. I don't ride mine in town too much, mostly country roads 40 to 60mph and regularly get 85 to 95mpg in UK measures.
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post #3 of 18 Old 12-19-2016, 02:39 PM
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I also can't help but notice that you go for months at a time without filling up. Make sure your filler cap isn't leaking or smelling gas anywhere; particularly if you keep your bike outside. That tank gets warm in the sun and vents. That gas could be going somewhere besides through your engine.

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post #4 of 18 Old 12-19-2016, 02:59 PM Thread Starter
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Quote:
Originally Posted by Keith View Post
Ye gods! Are you riding everywhere in first and second? Even accounting for the difference between US and UK measures (I assume you're US?) that's terrible. I don't ride mine in town too much, mostly country roads 40 to 60mph and regularly get 85 to 95mpg in UK measures.
Yes, I'm in first and second all the time. Using third gear is rare for me now. The numbers I gave were US (didn't realize UK gallons were larger until just now).

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Originally Posted by cbrlocal View Post
I also can't help but notice that you go for months at a time without filling up. Make sure your filler cap isn't leaking or smelling gas anywhere; particularly if you keep your bike outside. That tank gets warm in the sun and vents. That gas could be going somewhere besides through your engine.
It's not as bad as it looks on the graph because I forgot log a few fill-ups so those points are missing. I do park my bike outside, so I'll be sure check that. I've never smelled gas, but I can look around for leaks. I wouldn't see it on the ground because I park on grass, but is there a particular area on the bike I should check?
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post #5 of 18 Old 12-19-2016, 03:34 PM
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Well I'm pretty sure the short low gear riding is your cause. I'd suggest a long ride to help the engine clean out a bit.

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My Fuel Economy by
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post #6 of 18 Old 12-19-2016, 05:56 PM
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stop-start will use more petrol..
i use first gear for starting from a stop
or in an almost stopped situation..
once moving even slowly you should be
able to use second as low gear..

if someone wants to drag race [etc]
its full throttle, drop clutch, whereas
low speed riding uses low throttle openings
together with clutch to smooth out delivery
of power into drivetrain..

with broken traffic and stop start movement
best [imo] for motorcyclists to consider
themselves independent moving units,
withing the traffic.. eg, think of filtering,
whereby cars stop and inch forward etc,
within road car size road spaces..
wheras we continue in the bike space..

driver brains are conditioned to leave spaces
between their and other cars, incl both ways..
thus our space between them incl overtaking..

in slow moving and/or stopped lines of cars
overtaking can mean slowly drifting past
them, one at a time or as necessary..

cars bumper to bumper are trapped in their space
thus cant turn out even if they want to..
ie, its an element of safety for us..

just as racers learn and adapt to courses
so we should respond to varying condions
with appropriate strategies/riding skills..
smooth use of throttle and clutch etc
are always relevant..
one excellent practice for traffic etc
is very slow riding, feet on pegs..
riders can do specific practice sessions
which will extend into road riding..

6mth graph seems more rider adaptation
than ongoing systematic change etc..
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post #7 of 18 Old 12-20-2016, 10:27 AM
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Unless you get in top gear at cruising speeds, you won't get any decent numbers.

Stop and go riding in low gears will kill the mileage for sure, as will any time spent accelerating. Cold temps, and winter-blend gas, will drop mileage as well. Bogging in too high of gear won't help either.

Your new riding conditions may just be to blame.
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post #8 of 18 Old 12-20-2016, 11:30 AM
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If you're going 30 mph you can actually go in 5th gear. I do it all the time in city traffic. Not sure about the mileage as I rarely go through cities for long but I noticed a decrease in mileage when I followed the advice of some people here to go one gear lower through towns. Since you're going two to three gears lower I think that'll be the culprit.

I usually get 75mpg when I ride a mix of city, motorway and country roads.

My computer is fighting Aids and Cancer in it's idle time, and yours?
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post #9 of 18 Old 12-20-2016, 11:42 AM
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Quote:
Originally Posted by lightfox View Post
Yes, I'm in first and second all the time. Using third gear is rare for me now. The numbers I gave were US (didn't realize UK gallons were larger until just now).
There ya go. In fact, riding in just 2nd gear, I'm surprised you can pull 40+ MPG at all. I'm out of 2nd and into 3rd well before 20MPH, with 4th at 20 and 5th at 26'ish if flat and easy on the throttle.

1st - 0-12
2nd - 13-18
3rd - 19-24
4th - 25-30
5th - 31-~35
6th - 35+

These are my approximate shift points on flat level ground with light acceleration; some you can even go lower (5th gear is good usually from 25+ on flat ground). But it depends on the road, temps, and rider weight too. Just don't lug the engine.
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post #10 of 18 Old 12-20-2016, 01:58 PM Thread Starter
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Thanks for the feedback everyone. I'll try shifting sooner and then report back. I probably stay in 2nd gear up to about 28 mph. I'm out of town now for the holidays, but will change that when I get back. What RPM is the lowest I should go?
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