MPG nuances

[Khan]

So, I have been measuring the mpg on my 2009 Ninja 250 and I have taken many readings, the summary of which is as follows:
1. 44 mpg (mostly 65 mph)
2. 46 mpg (mostly 75 mph)
3. 46 mpg (75-80 mph)

Each of the above 3 readings is based on about 3-4 consecutive consistent values. So, I am quite confident they are free of error.
For reference, I have a 70 miles round trip to work which is mostly freeway (only 6 miles in town). Also I ride very conservatively (short shift often), fill up gas at the same Chevron near my house and always 91 octane rating. I even made a mark to make sure I fill it up exactly the same amount every time.

It confuses me why:
A) my Ninjette gives me a liter bike mpg
B) the mpg is lower at lower rpm (rpm at 65 = 7k, rpm at 75 = 9k). Shouldn't it be the other way around

Any thoughts ? Anyone else in the same boat?


UPDATE:
-After cleaning the air filter: 2.5 mpg increase
-After changing my riding style: 6 mpg decrease
-Increasing tire pressures: didn't yield any difference(if it did, it was too negligible to notice)

[Alex]

Potentially useful thread to start with:

https://www.ninjette.org/forums/showthread.php?t=13536

[Ghostt]

I get roughly about the same mpg, I have tracked my mileage using FUELLY on both my Ninjette and my EX500.

I've noticed that mileage also depends where I get my gas from, I've noticed the best mileage I get is using major brand, SHELL.





My Ninjette is set-up, gears 15/43 I'm 6'3" 220lbs with gear.

The Ninjette loves to rev, and the power band is up there, it starts about 8k and peaks at about 12.5k. Under that you could be lugging it, also shifting styles, like short shifting.

Is the bike stock? Any modifications? Carburetor tuning? Maintenance? Tire pressure?

A lot of factors can and do effect mileage.


FUELLY has app's, I use the android app.

[Panda]

Originally Posted by Khan

e Chevron near my house and always 91 octane rating.

You don't need to use 91. 87 is fine and is recommended.

[jkv45]

As Ghostt noted - is it stock? What size rider are you? How close to WOT are you when cruising?

Couple thing off the top of my head -

Use 87 octane without ethanol (if available). No need for 91, and it gives you less power and economy (assuming both are the same blend - E0 or E10) if you don't need the extra octane to prevent detonation.

Run a top quality synthetic 30 grade oil like Redline or Motul instead of a regular 40.

Keep an eye on the chain.

Consider a "double-bubble" type windscreen.

How recent are your results? Gas usually get reformulated around the middle of September, and mpg numbers will drop off. Gas with 10% ethanol can drop mileage up to 5%. Either way, you should really be seeing better numbers than that.

My '06 SV650 (naked) gets about 53 mpg at 75 mph on ethanol-free 87. Only significant changes are a slip-on muffler and a +1T countershaft sprocket, neither of which make much of a difference in mpg.

There are a ton of major aero mods you could do it you wanted to go that far for better mileage - an aero tail would probably show the most significant improvement, but it would be a major project. Removing the standard mirrors and going with a smaller bar-end mirror, and some flush-mount signals, are other things that could show improvements considering you are running at a fairly high speed for a significant amount of time.

[Motofool]

Originally Posted by Khan

.......... It confuses me why:
A) my Ninjette gives me a liter bike mpg
B) the mpg is lower at lower rpm (rpm at 65 = 7k, rpm at 75 = 9k). Shouldn't it be the other way around

Any thoughts ? Anyone else in the same boat?

My commute is like yours and for that, keeping 10K rpm / 80 mph (indicated), my naked 250 pre-gen consistently covers 55 miles per each gallon of regular gasoline+10% ethanol.

At lower or higher rpm's the engine has to overcome the resistance from air and rolling.
The useful work that is generated by the combustion of the fuel is the same in both cases.
In theory, for same sustained speeds:
Low rpms x more opened throttle = High rpm's x less opened throttle

Nevertheless, each case has its particular losses of work and heat to overcome useless resistance (internal friction, gases turbulence, compression leaks (through rings and valves), incomplete filling of the cylinder, less than ideal timing (for sparks and valves), etc.).
Those are the reasons for each engine to have a curve that shows its efficiency along the range of rpm's that is capable of.
Efficiency meaning amount of delivered useful work per unit of burned fuel for an specific rpm.
As the picture below shows (sorry, I could not find one for the Ninja 250), keeping the rpm's close to the peak efficiency for your commuting speed makes the real difference in economy.

What saves gasoline is not the rpm's at which you upshift, but how you manage the energy stored in that liquid.
Sustained high speeds, strong accelerations and short trips are the real killers, considering that the machine is in optimum conditions.

If you are rolling with a poorly lubricated chain, with a slipping clutch, with dragging brakes, with out-of-adjustment carburetors, with dirty air filter, with under-pressurized tires and with non-calibrated valves, you will be burning extra fuel just to deal with those issues.

[Khan]

Thanks for all the replies. They cleared up a bunch of misunderstandings on my part (like short shifting, power band etc). Here are the specifications that I didn't mention earlier:

a. Mods: None at all. The bike is completely stock.
b. Carburetor tuning: I have gotten the carburetor cleaned once and rebuilt once (2 months ago) from a well known motorcycle shop. Got it rebuilt bc the mechanic recommended it due to slight wear on the rubbers. I thought it was extraneous but I use the bike a lot. So, went with it. I don't really know if there is a specific set up (noob alert)
c. Maintenance : Done on time if not earlier. Ride all year around (OC, California)
d. Tire pressure: Front 28 psi, Rear 32 psi. Tyres are Kenda K671 so they last longer
e. Gas: I started using 91 after the same mechanic recommended it due to the bike not being fuel injected and the possibility of the carburetor being clogged by low quality gas. I took his word for it based on his experience. However, if thats not the case, I'd rather not waste my money
f. Rider: I am 5' 7.5", weigh 145 lbs (+10 lbs of luggage)
g. Result timing: I have been taking the results for 3 months now. The ones at 75-80 mph are the most recent ones
h. Engine Oil: Mobil1 10W40, Full synthetic. Is it better to run 10W30?
i. Chain: Well lubricated, usually clean and lube it every month and a half
j. Air Filter: Cleaned it after reading your replies

I noticed 10% ethanol mentioned in your guys' posts. Is it added separately or pre-mixed with the gas we buy? (noob alert again)

Thanks again

[csmith12]

You're in CA... It's already in the pump gas, nothing to mix. It should say the amount of ethanol right on the pump (sticker, most likely a yellow square). It's gunna be 5%, 10% 15% or ethanol free if your lucky.
Pump 87 is enough and highly recommended, many of us race on that fuel.
Your weight is fine to get higher mileages and there is nothing wrong with your oil choice.
Although for the straight line commuting stuff, you could raise the psi a few lbs to save a bit of your tire as well as help keep the mpg up.

Good luck!

[Motofool]

Originally Posted by Khan

.........
i. Chain: Well lubricated, usually clean and lube it every month and a half........

I recommend lubrication of the chain every time that you refill the fuel tank or 200 miles.

Learn more about the reason for that:
https://www.ninjette.org/forums/showthread.php?t=133019

More about mixed fuel:
https://www.ninjette.org/forums/showthread.php?t=139224

[jkv45]

If you are using regular Mobil 1 10W-40 auto oil - I would change. No standard auto oils are a good choice for cycle engines due to low levels of special additives (ZDDP) you need with solid-lifter style valvetrains.

Mobil 1 10W-40 "4T" cycle oil is fine if you are using that. Rotella T6 5W-40 is a good inexpensive cycle-safe oil for general use.

The only 30-grade oil I would use be an Ester synthetic like Redline or Motul 10W-30. It's far superior to any 40 grade conventional oil, and because it flows easier when hot would most likely show some mileage increase at those speeds and revs.

In CA you aren't going to find ethanol-free gas, so there's no choice there. As far as running a "Premium" gas - that's a joke for the most part. It's typically no better than lower grade gas from the same manufacturer. If you want a fuel system cleaner, run Techron Concentrate (1oz per gal) once a year - don't buy Premium just because it has more detergents.

I would question some of what your mechanic has told you. If it was running well, I don''t think a carb rebuild was required because the "rubbers" (did he explain what that was?) were showing wear, plus his recommendation to use Premium gas because the carb was clogged by low quality gas was off the mark IMO.

[spooph]

agreed with all of this.

I would recommend being scientific about this. Before you change anything, take some readings changing your riding like this:

1.) Accelerate to the speed limit taking each gear to 10 or 11Krpm's.
2.) Once at the speed limit, shift to top gear.
3.) If you need to accelerate, downshift as many gears as is needed to accelerate above 6K RPM's.
4.) Once you've accelerated, shift to top gear.

Run 3 tanks like this and see if anything changes.

[Khan]

Originally Posted by jkv45

If you are using regular Mobil 1 10W-40 auto oil - I would change. No standard auto oils are a good choice for cycle engines due to low levels of special additives (ZDDP) you need with solid-lifter style valvetrains.

Mobil 1 10W-40 "4T" cycle oil is fine if you are using that. Rotella T6 5W-40 is a good inexpensive cycle-safe oil for general use.

The only 30-grade oil I would use be an Ester synthetic like Redline or Motul 10W-30. It's far superior to any 40 grade conventional oil, and because it flows easier when hot would most likely show some mileage increase at those speeds and revs.

In CA you aren't going to find ethanol-free gas, so there's no choice there. As far as running a "Premium" gas - that's a joke for the most part. It's typically no better than lower grade gas from the same manufacturer. If you want a fuel system cleaner, run Techron Concentrate (1oz per gal) once a year - don't buy Premium just because it has more detergents.

I would question some of what your mechanic has told you. If it was running well, I don''t think a carb rebuild was required because the "rubbers" (did he explain what that was?) were showing wear, plus his recommendation to use Premium gas because the carb was clogged by low quality gas was off the mark IMO.

Thanks for the recommendations, I will defer to the Rotella T6 next time I change my oil and will post if the mpg changes

Originally Posted by spooph

agreed with all of this.

I would recommend being scientific about this. Before you change anything, take some readings changing your riding like this:

1.) Accelerate to the speed limit taking each gear to 10 or 11Krpm's.
2.) Once at the speed limit, shift to top gear.
3.) If you need to accelerate, downshift as many gears as is needed to accelerate above 6K RPM's.
4.) Once you've accelerated, shift to top gear.

Run 3 tanks like this and see if anything changes.

After reading the power band explanations by previous posters yesterday, I started following your suggested method since today coincidentally (except point 1, I shifted at about 7-8k and stayed away from short shifting)
However, I felt the bike a bit more responsive today. Is it possible that cleaning the air filter(which was pretty dirty. took me 15 mins of dish detergent rubbing to clean it enough to be acceptable) can cause a noticeable difference or is it just psychological? Moreover, I should be refilling my tank soon and if the air filter caused any mpg changes, it should be apparent. I wonder if it will change from a singular factor.
Also, is it ok to re-use the filter or should I just buy a new one?

Thanks

[allanoue]

Originally Posted by Khan

. Is it possible that cleaning the air filter(which was pretty dirty. took me 15 mins of dish detergent rubbing to clean it enough to be acceptable) can cause a noticeable difference or is it just psychological? Moreover, I should be refilling my tank soon and if the air filter caused any mpg changes, it should be apparent. I wonder if it will change from a singular factor.
Also, is it ok to re-use the filter or should I just buy a new one?

Thanks

Get a straw and go for a run only breathing though it, and try not to pass out. It is not psychological. Some air filters can be reused. Get a K&N air filter. It will let lots of air though and will be the last air filter you need to buy.

[cbinker]

Run closer to Max tire pressure and your MPG will improve.

[jkv45]

Originally Posted by Khan

Thanks for the recommendations, I will defer to the Rotella T6 next time I change my oil and will post if the mpg changes

Rotella is pretty much a go-to for a lot of cycle owners. It has everything you need, is relatively inexpensive and easy to get, and is superior to almost all conventional oils in the same range.

I don't think you will see any mpg increase running T6 over what you are using though, just better engine protection.

[spooph]

you can definitely re-use the foam air filter. If it doesn't have any tears in it, it is good! Using the right air filter oil will also help it perform at max performance.

Something like this:


any foam air filter oil will work, doesn't have to be kawi or a high-end brand. I do my air filter every oil change, after a while it becomes second nature.

there are also kits available: http://www.motosport.com/no-toil-filter-maintenance-kit

Notoil is some pretty good stuff!

[verboten1]

Originally Posted by Khan

It confuses me why:
A) my Ninjette gives me a liter bike mpg
B) the mpg is lower at lower rpm (rpm at 65 = 7k, rpm at 75 = 9k). Shouldn't it be the other way around

A) carburetors
B) pumping losses.

[xXecuterXx2]

Originally Posted by verboten1

A) carburetors
B) pumping losses.

Pumping losses? I'd say that also has to do with carbs

[Khan]

It cant be the carbs, they were just cleaned 2 months ago. The mechanic at the shop sent me pictures of the dirty carbs to prove he opened all of it up and cleaned it properly.
Plus, the bike was bogging down a LOT before that due to the carbs, it is not anymore which is another evidence of him cleaning them.

Another interesting thing came to my mind today from all the useful input I have gained from the forum members in the last 2 days. Since I am implementing a number of changes on the bike (many of them much needed due to my unawareness), I will keep a log of all of them and measure the mpg (3-4 readings) while keeping all the remaining variables the same to calculate how much difference each makes. Following are the ones I have noted so far:
1. Engine Oil (changed 1 month ago, mpg changed from 45 to 47)
2. Air filter (not enough data yet)
3. Tire pressure
4. Avoid short shifting/ try to stay in the power band

I have already implemented no.2, so I will keep the others the same until I have 3-4 tank fill ups

[Khan]

Originally Posted by spooph

you can definitely re-use the foam air filter. If it doesn't have any tears in it, it is good! Using the right air filter oil will also help it perform at max performance.

Something like this:
any foam air filter oil will work, doesn't have to be kawi or a high-end brand. I do my air filter every oil change, after a while it becomes second nature.

there are also kits available: http://www.motosport.com/no-toil-filter-maintenance-kit

Notoil is some pretty good stuff!

After reading your post, I read the other thread on the forum to find out the proper way to maintain the air filter. I just washed it with dish detergent and put it back in after drying it, didn't use a proper filter cleaner or put any oil on it. So I will repeat the process on the weekend and see if it makes a difference in the power/mpg. Thanks

[BrianATX]

I also have better mileage at lower speeds. If I spend time cruising around downtown I make a mental note that the next fill up will be enhanced. Downtown commuting I never get close to the rev limiter and maintain much lower speeds. Otherwise I routinely shift in the 12k+ range. In my everyday commute when at the legal speed (adjusted) I switch to a gear that allows me to cruise at 6-8k RPM. My commute to work is about 20 miles at 60-70 MPH and I average 52 MPG. I expect my speed to be at least 5 MPH slower that what is displayed on the gauge. I presume that if going 80 MPH my acutal speed is 72 MPH.

I primarily fill up with Shell 87 octane 10% ethanol. I have found that Shell provides better mileage on my bike and cars. Tip: Getting a FRN card saves 3 cents a gallon at Shell. For tire pressure I run 37 PSi in both (Bridgestone BT45) and it makes a tremendous difference. Pushing around the bike is noticeably easier and I found myself having to use the brakes more with engine braking. I always lube the chain after every fill up with Dupont Chain-Saver. I use Rotella T6 5w-40 motor oil.

My fuel gauge is accurate however I do not calculate the full volume of the tank. I assume F is 4 gallons and E is 0.8 gallons remaining. The last 0.8 gallons go unused by myself thus far. When I get to the first marker of 1/8th spent on the fuel gauge my trip odometer will show a few miles over 25 miles traveled. This pace of usage reflects well with my average MPG and continues till the gauge is on E. I am curious how much of the tank you can drain fuel from before you are below the level of the plastic fuel filter. Has anyone pulled that filter off their fuel spigot? How much did you drain from the tank with it on versus off? I have a line filter so I am tempted to test this myself one day.

My experience was accumulated over 28k miles on a 2008 that has a Jardine RT5 exhaust system, K&N air pod, and upgraded Klein idle jet size 40 and Klein main jets size 110. Front sprocket is +1 which did not effect mileage. Exhaust was installed when I bought the bike so I do not know the effect it has. The K&N air pod provided another 3-5 MPG with the jet and carburetor changes made at the same time. My bike is black so a green bike may perform better.

Ghostt: Thanks for telling us about Fuelly. I just signed up and I already feel the need to apologize to the people behind me waiting to use the pump. I expect I will be fumbling with my phone wearing gloves trying to type in mileage and fuel stats after every fill up.

[InvisiBill]

Originally Posted by BrianATX

Ghostt: Thanks for telling us about Fuelly. I just signed up and I already feel the need to apologize to the people behind me waiting to use the pump. I expect I will be fumbling with my phone wearing gloves trying to type in mileage and fuel stats after every fill up. :)

If you need to hurry, take a picture of your gas receipt next to your odometer (or just two pics of the gas pump's display and your odometer, if you don't like receipts) and enter the info later.

[jkv45]

Originally Posted by BrianATX

I primarily fill up with Shell 87 octane 10% ethanol. I have found that Shell provides better mileage on my bike and cars. Tip: Getting a FRN card saves 3 cents a gallon at Shell. For tire pressure I run 37 PSi in both (Bridgestone BT45) and it makes a tremendous difference. Pushing around the bike is noticeably easier and I found myself having to use the brakes more with engine braking. I always lube the chain after every fill up with Dupont Chain-Saver. I use Rotella T6 5w-40 motor oil.

Can you get ethanol-free in Austin?

If so, I'd give it a try to see what it gives you. Engines react differently, and F.I. will made adjustments to compensate. To get the most out of it with carbs you would need to make adjustments to the mixture, but it still may show improvements in mpg without making any changes.

[250rr]

Originally Posted by jkv45

If you are using regular Mobil 1 10W-40 auto oil - I would change. No standard auto oils are a good choice for cycle engines due to low levels of special additives (ZDDP) you need with solid-lifter style valvetrains.

I used to think this as well. I read this post from another forum (I know. I know. For shame!) Interesting, if nothing else.

http://www.ducati.ms/forums/80-hall-...otorcycle.html

[BrianATX]

Originally Posted by jkv45

Can you get ethanol-free in Austin?

If so, I'd give it a try to see what it gives you. Engines react differently, and F.I. will made adjustments to compensate. To get the most out of it with carbs you would need to make adjustments to the mixture, but it still may show improvements in mpg without making any changes.

In the last 7-8 years it seems like every station in the city has switched over to have 10% ethanol. I expected I could find a old mom and pop station nearby but I went to Pure-Gas.org and they have a nice map feature that induced a bit of laughter as I zoomed into central Texas. The nearest ethanol free gas station to me is 70 miles away.

[jkv45]

Originally Posted by 250rr

I used to think this as well. I read this post from another forum (I know. I know. For shame!) Interesting, if nothing else.

http://www.ducati.ms/forums/80-hall-...otorcycle.html

That oil (15W-50 Mobil 1) isn't a standard auto oil, so it does have higher levels. The only 10W-40 auto oil that Mobil 1 lists (https://mobiloil.com/~/media/amer/us...pecs-guide.pdf) is "High Mileage", and it also has more than standard levels - but it still isn't a better choice than Rotella T6.

Running a 15W-50 isn't a great idea if the engine isn't designed for it. 15W is WAY too heavy for anything resembling cold temps, and 50 is not a great choice for engines that recommend 40. Heavier oil moves slower and carries heat away slower. Heavy oil also builds more oil pressure that necessary. Heavier oil is not better, with the possible exception of a Big Twin running a conventional oil...in the middle of summer...stuck in traffic...

Just run Rotella T6 and call it a day.

[verboten1]

Originally Posted by Khan

It cant be the carbs, they were just cleaned 2 months ago.

Sure it can. It's not fuel injection

[Flying]

When I was commuting on the bike I got roughly 10-15 mi/gal over the OP in less than ideal weather conditions. Like others, I'm inclined to say the primary problem is a tuning issue that can be corrected, rider error, or both.

It's exciting to see you handle this systematically Khan. Particularly interested in the change of shift point.


Don't discount the carbs though, they can be finicky at times.

[Khan]

Just to make the information easier to attain, I will also add the information to the first post as an update:

After changing the air filter: there was a 2.5 mpg increase (based on multiple fill-ups)

Next on the list, riding style change by staying in the power band and avoiding short shifting