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"Poor" Gas mileage - Any Advice?

30K views 107 replies 34 participants last post by  R Runner 
#1 ·
Everyone,

I purchased a used 2012 CRB250R with 248 miles on it on June 1. The purpose for purchasing the bike was to get the excellent mileage that most people seem to be getting. When I went to look at the bike, I noticed that it had a Two Brothers Exhaust Since I am strictly interested in gas mileage, I asked the dealership to replace the aftermarket exhaust (slip on) with a factory exhaust. At the very least, I wanted to start with an "all factory" bike. The first few tanks yielded about 70 MPG with very very limited high RPM riding. Nearly all of my riding was on state highways at about 60 mph.

To improve the mileage, I deceided to go with the 15/36T gearing that is available from PMP. I changed gearing and my mpg went from 70 to 75 MPG. Others on the forum were talking about getting 90 or better.

To further improve my mileage, I made a 17T for the front. After a little bit of effort, I made it work. However, I am still only getting 80 MPG.

I measure my fuel ups very carefully using methods found on this forum and proven to work. I also purchased a Speedohealer and programmed it correctly. I have not only compensated for the gearing, but also the factory error. When I get on the interstate, I compare my odometer to the mile markers, and it is spot on. It took me several runs to fine tune, but now it is repeatable and consistent.

I have tried to reset the ECU at about 1350 miles thinking that the previous owner ran the bike hard and that the computer "learned" this style of riding. I found out that he traded in the bike for a CBR1000RR claiming that the 250 did not have enough power. The other thought I had was that he actually reprogrammed the fuel curve (or had some one else do it) to get as much power out of it as possible. Anyway, I tried to reset the ECU but am not sure I did it correctly. I followed both the shop manual and on line help I found but did not get the correct flashing lights (MIL) that I was told to expect. I rode a bunch of highway miles immediately after the ECU "wipe". To no avail... 78 MPG.

My next plan is to take it to the Honda Dealer to have them check it out and see if there is a program in there or at the very least put the ECU back to stock. Another option is to purchase a programmer and adjust the fuel curve myself, but I want to avoid doing that at this point because I should not be having these issues with the stock setup.

I have not pulled the door from the air box and I am not hypermileing, but I am tucking above 60 mph for multiple reasons.

Anyone have any thoughts on why I'm seeing this mileage and not 90 MPG or better?

Thanks for the help.
 
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#6 ·
Actually I did do a little crazy stuff. I made a 17T for the front. The largest offered, that I know of, is a 15T. My ratio is about 28% taller than stock.
 
#5 ·
I agree with the others getting 65ish mpg. That is what I finally started getting after about a thousand miles. I usually go wot up to about 60-65mph and just cruise there. I am a good sized guy, 6'1" 210lbs and usually get 66mpg. Very happy with the mileage. You shouldn't be upset about 80mpg, like you said you aren't hypermiling the bike.
 
#7 ·
After reading a the posts so far, maybe my original 70 mpg is not so bad. However, Honda claimed 77 mpg. Also, there have been several others who have posted 80+ mpg on standard gearing.

I would really like to know what I am doing differently.

Thanks for the replies so far..... :)
 
#12 ·
It's not your ECU adaptation. You are doing fine. Very few people break 80 mpgUS. Your gearing may be too long in 6th for 50 mph so you are lugging too much throttle at 4000 rpm. The best BSFC for this engine should be between 5-6000 rpm. At lower speeds you can milk 4000 rpm at 35 mph with an easy throttle. Here are some tips for hypermiling.
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100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com
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#21 ·
It's not your ECU adaptation. You are doing fine. Very few people break 80 mpgUS. Your gearing may be too long in 6th for 50 mph so you are lugging too much throttle at 4000 rpm. The best BSFC for this engine should be between 5-6000 rpm. At lower speeds you can milk 4000 rpm at 35 mph with an easy throttle. Here are some tips for hypermiling.
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100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com
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Sendler.... I was hoping you would respond. Thanks for the input on the ECU. I am trying to make a point to not run to low on RPM. I shift to 6th at 60 mph and not before. That equates to 4800 rpm with my current gearing. Yesterday I ran the insterstate to try to duplicate some of your 80% interstate riding thinking that all of my stops on the state highways were hurting my mpg. Apparently I was wrong. 95% of my ride yesterday (122.8 miles in total) was interstate at about 68 mph (5600 to 5700 rpm) and tucked the majority of the time. Actually I'm having trouble pulling 6th without being tucked at that speed. Anyway, I like being tucked because there is less wind kicking me around.

At lower speed I am doing what you are talking about. Very slight throttle at about 3500 to 4500 rpm. I try to never lug the motor. I'm very sensitive about that.

I also have checkout the hypermiling link, but want to get some "real world" driving incorporated into my numbers. I know it sounds counter productive, but I have an overall goal in mind.

Thanks again for your response.
 
#13 ·
I get about 79.3 average over the past 2600 miles tracked. Riding it on the hard side and am impressed at the mileage.... One look at the CBR600RR figures and I am happy to be riding a CBR250R!
 
#15 ·
Adjusting Riding Operations for Different Gearing.

Everyone,

I purchased a used 2012 CRB250R with 248 miles on it on June 1. The purpose for purchasing the bike was to get the excellent mileage.

The first few tanks yielded about 70 MPG with very very limited high RPM riding. Nearly all of my riding was on state highways at about 60 mph.

To improve the mileage, I deceided to go with the 15/36T gearing that is available from PMP. I changed gearing and my mpg went from 70 to 75 MPG.

To further improve my mileage, I made a 17T for the front. After a little bit of effort, I made it work. However, I am still only getting 80 MPG.

I have tried to reset the ECU at about 1350 miles. I rode a bunch of highway miles immediately after the ECU "wipe". To no avail... 78 MPG.

Anyone have any thoughts on why I'm seeing this mileage and not 90 MPG or better?
Some information to think about.

The main Reason your mileage is below your expectation is you're still operating your cbr as if it had the stock gearing installed.

To increase the cbr's mpg, you will have to operated your cbr in a manor that will make the best use of the gearing change.

With the stock gearing, 14/38 at 6,800 rpms your speed would be 68 mph.

With the gearing set, 15/36 at 6,800 rpms your speed would be 77 mph.

With the gearing set, 17/36 at 6,800 rpms your speed would be 87 mph.

What is occuring with the gear changes. You are lowering the engine's operating rpms below the best effencient power peak of the engine (peak torque).

Your gearing change has put your cbr into a different operating class. It's no longer a general use motorcycle.

It's geared for high speed highway travel only. Not for city, short trips or enjoying the twisties.

Look at sendler gearing. The type of riding that his cbr is operated in for the most time.

Like most changes. Their is always a trade off. In your case, some loss of accelerating from a stop. The gain is a higher crusing speed. To realize this gain, you have to alter how you operate your cbr.

From a stop, accelerate in each gear to 6,800 rpms or higher. When you reach your crusing speed, adjust the throttle as necessary to maintain that speed. If you have to slow down and then accelerate. You will have to adjust the gear changes to keep the engine's rpms at the optimum point. The longer you operate in a lower gear than 6th, you wasting energy.
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#17 ·
Personally, I think anything over 75mpg is a winner. Honda's EPA estimated mpg, is calculated by riding very conservatively which I know we all don't most of the time.

When I first got my bike, I rode the streets, cruising @ 5k or so. After a few tanks, I averaged 85mpg. Never going beyond 6k rpm, and 60mph. All slow and smooth.

When I started doing the highway, my mpg shot down to about 65-75mpg. Still great. I recently went on a 200mile trip, filled the tank 2.8gals, that's 71mpg, going 75mph the entire time, with some strips going 85mph, and running 99mph when I tested my top speed.

All in all, don't do so crazy over all these attachments to control your MPG that much. Honestly, if you care this much for MPG, and you are willing to spend your time and money on all these small upgrades for better mpg, no offense but get an electric car if you want that type of miles without gassing up the tank.
 
#18 · (Edited)
Greetings R Runner,

I admire and respect your Search for Higher Gas Mileage for your CBR. You will hear a lot of information about why you Should Not. I for One, support your Quest.

Myself for one, has spent the last 7 years doing MPG research on my Rebel 250.

Later today, due to a Doctor's appointment. I post some information about my quest for higher mpg.

The greatest news first. Over 100+ mpg on a 8,600 mile adventure, with an average speed of 76 MPH recorded with a Garmin 255w gps.
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Display of Garmin 255w GPS.


.
K
Keep the Faith and Dream alive. You don't loose the Fun Factor with your Gearing Change.
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#19 ·
I've only calculated millage on one tank so far but was pleased to see just over 80 miles per US gallon.

I wasn't riding for MPG but I wasn't beating the crap out of it either. I only weigh 145 pounds, not sure if that would make a big difference or not.
 
#22 · (Edited)
I finally had a chance to read through all of the responses so far. Thank you all for your input. Here are a few details that will help put the whole picture together.

- The reason I am put on taller gearing is because I am in the process of building a streamliner. The intent is to make the vehicle a daily driver with cargo space, and protection for the driver and passenger. It will not be a show piece.
- To do this I need a good base line. I have a rough base line with stock gearing. I really thought that the taller gearing would help, but I am starting to think that the aerodynamics of the bike will not allow me to take full advantage.
- I want to make sure that my current setup does not have any "issues" or items that ae holding back my mpg.
- It is a project. I'm not going to disagree that there are some impractical points like cost vs. payback. IF I truly acomplish my goal, I will be able to replace a car with it. That will have the biggest impact. Most motorcycles are in addition to the cost of a practical year round vehicle.
- The payback for my current situation is 6 years at $4.00 per gallon gas.

So again, this is a big picture project. I'm really excited and happy to have recently joined the community. The Vetter challange may be in my distant future, but not my goal.

Back to the topic.....

Do we know the optimal RPM range? I was always under the impression that it was the lowest RPM that could be maintained under about 1/2 to 2/3 throttle. considering that highway use is needed, this may not be practical UNLESS you had a really tall gear and could minimize the rolling and aerodynamic drag.

I'm trying to figure out how running at higher RPM is helping the mpg.

Also I do make sure I run to atleast 5500 RPM before shifting. My rpm change per gear is high enough that it is now required.

BTW.... I miscalculated... I got 79.74 mpg on the interstate, not 78 mpg.
 
#23 ·
More Information.

The reason I am put on taller gearing is because I am in the process of building a streamliner. The intent is to make the vehicle a daily driver with cargo space, and protection for the driver and passenger. It will not be a show piece.
Could you give us some general information about the project and what your idea's are for the engine performance. Top Speed, highway crusing speed - interstate and secondary roads.

Target Highway and city speeds and projected mpg at these speeds?

This information would be most appreciated.
.
 
#26 ·
The frontal area of the bike will be about 7.75 square feet. If 5 feet of that is useable, and there is a 4 foot section in the middle, I'll have at least 20 cubic feet. Granted, that is not in addition to a passenger, but it will have much more carring capacity than most bikes. I want to be able to go to the hardware store and pick up "stuff". I am considering the suspension and I agree that it may be necessary to change the coil over to handle more weight. The anticipate additional dry weight to the bike will be between 160 and 190 lbs. The CBR250R front suspension may be too light as well. We will see. If so, I'll put in a different fork assembly. After measurement, I think the best choice is a CBR1000RR. Many pieces of the bike will be removed. I'll use the front frork assembly and frame with drive train and tank. All other items can be removed and stored until I decide to replace the bike.

I expect that it will look a little crazy. That's okay, I'm used to people looking at me funny.
 
#34 ·
hi r runner, did you have a look at the swiss ecomobile? enjoy
Thank you bongiorgio. I took a look at this one last year. I like the concept, and it looks fun, but it seems very expensive for the mileage you would get. I think I can do better as far as bang for the buck.
 
#31 ·
I've been getting 78 mpg (US). Most riding between 45-50 mph, with some 35 and some 55 mph. Upshifting per Honda recommendations in the owner's manual, i.e. fairly early low-rpm shifts under gentle acceleration. Since I passed the 600 mile mark and had the first valve service done, I feel more confident in revving the bike more and my mileage will probably go down a bit. Today I was letting the bike run 6000 rpm at whatever speed I was cruising at...much more fun to have some power on tap! I will need to start logging after my next fill-up to see what impact this has on mileage.
 
#35 ·
Everyone,

Thank you for the mpg feed back. Again, I think that I should be getting better mpg based on your comments. With stock gearing, I was only able to get 70 mpg. It sounds like I am about 5 mpg low.





shisoshin.... I'm not sure I understand. Are you saying that I'm making this up? Just curious.
 
#38 ·
I am not sure what I am getting on mpg, but I travel 120 miles a day to and from work back home. I go about 75 MPH on the I-70 in western md going down towards baltimore md ( Washingtion county to Howard county ) I fill the tank up, half of the time I have six bars ,while other times I only see 5 bars on the gas gauge! When I get home, I always have 1 to 2 bars left. I think I am getting about 60 to 65 mpg. that extra 12 would be nice but If I have to do 55 mph to get 77 mpg, I will never see those figures. I dont drive slow.
 
#39 ·
Thanks for all of the feed back so far guys.

Any other stories on MPG? So far I am starting to feel better about the MPG I'm currently getting.

As for the project:
I can tell that some doubt the logistics, but I am confident I can make it work. I have spent about 3 to 4 months designing, purchased the majority of the frame material and have been cutting and welding aluminum for the past 3 weekends.

A waste of time? An impossible goal? I guess I'll find out. I learned a lot and met a lot of cool people while building my last vehicle, I can hardly resist doing another one. :)
 
#41 ·
Soul Searcher...


I agree with your post and the definition given. It is consistent with what I was taught in school as well. The internal combustion engine is not very efficient in general.

I look forward to your thread on gearing.
 
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