Disabled accelerator pump = better MPG - Wrist Twisters
 
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post #1 of 15 Old 09-12-2008, 02:56 PM Thread Starter
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Disabled accelerator pump = better MPG

Let me start by saying I usually read posts about gas mileage skeptically because based on the broad range of of reported MPG for the 919 I have concluded that it is very subjective. Too many variables to establish a guaranteed MPG for any one machine. Rider weight, rider seating position, altitude, How much throttle used to accelerate onto freeway, city driving, odometer accuracy, calculation accuracy, the amount of fuel pumped into the tank at any given time can be varied by ambient temps and if the bike is on a side stand or center stand or you are sitting on it or how full you get it. The list goes on and on and on and on. Basically, you can only compare MPG against similar scenarios etc.

All of that said, I wanted to share that I have confirmed over the last 3 tanks of fuel that I am getting significantly better MPG after turning OFF the Accel Pump feature for the Power Commander 3 usb. I would consistently get between 28 to 32 MPG with an occasional 34 over the last 4 yrs I have owned it after installing the speadohealer and calibrating for speed, not odo. My 2003 has 23,200 miles as of yesterday. Ya ya.. I know some of you get 50 MPG blah blah.. I weight more, block more wind, wheelie more, ride harder, ride faster, have different gears etc. With the Accelerator Pump feature disabled I have got 34+, 35+ and this last tank got 36.5 MPG. Now that's mixed city and freeway and lots of short trips and plenty of traffic lights and wheelies and warm-ups etc. No real change in my riding habits at all. Just wanted to share what I am convinced has happened.

I will continue to monitor my MPG at every fill-up and might report back if things continue or change. As always, your mileage may vary... quite literally.

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post #2 of 15 Old 09-12-2008, 03:30 PM
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Although confirmation is difficult to get from Honda (Actually, impossible is closer to reality.) I am convinced that the stock ECU has an accelerator pump function based on the rate of increase of the TPS value when the throttle is opened, so you disabled one of the two your 919 has. I draw this conclusion from a conversation with a Honda auto tech school instructor and the manners of the engine when screwing the throttle on. I have also noticed a drop in mileage when high speed lane splitting due to the "make sure of the situation then blow by" way I do things.

Incidentally, I have also logged a 9 to 10% increase in mileage after building and installing my low and narrow lane splitter bars, which should come as no surprise considering the smaller frontal area and the habit I've developed of laying down on the tank and keeping my left hand on the seat behind me instead of holding onto the left grip.
On a side note, at freeway speeds it will gain 4 to 5 mph when I drop into a tuck while keeping the throttle steady.

Rob

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post #3 of 15 Old 09-12-2008, 09:57 PM
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Thanks for all the info guys. Makes a PC3 more intriguing. I know there are mixed reviews and some saying that its not necessary, but I have always been curious.

'04 919---40k----6/18/10 SOLD

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post #4 of 15 Old 09-13-2008, 07:43 AM
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Ive as of yet been unable to get anything lower then 42! I think I must average like 48. Thats city/highway/and everything in between. I'm 185lb and 6'1", so I have doubts its my aerodynamics :P
I "short shift" as some people would call it. I rarely have to get to 5k for any reason while commuting/cruising, and usually in traffic etc will shift before 4k. (3k if traffic is slow!) I really think thats the difference between peoples MPG figures right there. More RPM = more fuel (unless your trip is entirely downhill and your engine braking the whole way! ). Otherwise something is not functioning to standards.

I got 50 on my almost entirely highway trip to boston a few weeks ago.. I do have fun on it too, I just have not found many nice enough roads to desire putting 65 lb/fts to the ground for any length of time! The one time I did get 42 was after chasing a buddy through the twisties for over half an hour, keeping the revs up.

I get 45ish mpg on my 600+lb '82 CB900c also, and that bike is running pretty crappy right now. That thing is an aerodynamic brick and has almost 150 lbs on the 919.

So yeah thats my take on the situation. MPG is directly proportionate to where you like to keep the needle on the tach. And the more range you have the more varied it gets. 250 owners will claim anywhere from 50 to 80!

--Dan

oh and hi this is only my 2nd post!

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post #5 of 15 Old 09-13-2008, 08:09 AM
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Ok, out of curiousity I turned mine off this a:m before riding in to work, I had mine set more towards the "race" settings and I've had quite a bit of "herky-Jerky" throttle response during shifting, with the accelerator pump off it does feel like it's smoothed out a bit. I'll run it a while longer to see if it's just my imagination.
I've been getting decent mileage (around 40) it'll be interesting to see if that improves.

Dan

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post #6 of 15 Old 09-13-2008, 02:47 PM Thread Starter
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Quote:
Originally Posted by dr1 View Post
...
I "short shift" as some people would call it. I rarely have to get to 5k for any reason while commuting/cruising, and usually in traffic etc will shift before 4k. (3k if traffic is slow!) I really think thats the difference between peoples MPG figures right there. More RPM = more fuel (unless your trip is entirely downhill and your engine braking the whole way! ). Otherwise something is not functioning to standards.
...
So yeah thats my take on the situation. MPG is directly proportionate to where you like to keep the needle on the tach....
Gotta be! I do have ya by 100 lbs tho. For me, 5k on the tach is a relaxed stroll to the get groceries. I run 15/45 sprockets and I frequently see 8000-10000. I smack the rev limiter at least twice a tank. Damn thing has a job to do.. excite me!

Ya, pretty sure 50 MPG is easily possible with a conservative approach to the throttle. My point was I didn't change the way I ride. I only changed the Accel Pump to disabled. That's all! Gotta compare what ya got before and after this change on the same bike with same habits.

Enjoy!

- Rev. CYCHO -

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post #7 of 15 Old 09-13-2008, 08:29 PM
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i will never see 50mpg and i'm o.k. with that

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post #8 of 15 Old 09-13-2008, 09:49 PM
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Quote:
Originally Posted by MotoCycho View Post
Gotta be! I do have ya by 100 lbs tho. For me, 5k on the tach is a relaxed stroll to the get groceries. I run 15/45 sprockets and I frequently see 8000-10000. I smack the rev limiter at least twice a tank. Damn thing has a job to do.. excite me!
Quote:
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i will never see 50mpg and i'm o.k. with that
/\ I'm with them ++ /\ I officially observed and stretched 1 tank of gas, the rest has been burned as rapidly as possible.

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post #9 of 15 Old 09-14-2008, 04:08 AM
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Quote:
Originally Posted by dr1 View Post
Ive as of yet been unable to get anything lower then 42! I think I must average like 48. Thats city/highway/and everything in between. I'm 185lb and 6'1", so I have doubts its my aerodynamics :P
I "short shift" as some people would call it. I rarely have to get to 5k for any reason while commuting/cruising, and usually in traffic etc will shift before 4k. (3k if traffic is slow!) I really think thats the difference between peoples MPG figures right there. More RPM = more fuel (unless your trip is entirely downhill and your engine braking the whole way! ). Otherwise something is not functioning to standards.

I got 50 on my almost entirely highway trip to boston a few weeks ago.. I do have fun on it too, I just have not found many nice enough roads to desire putting 65 lb/fts to the ground for any length of time! The one time I did get 42 was after chasing a buddy through the twisties for over half an hour, keeping the revs up.

I get 45ish mpg on my 600+lb '82 CB900c also, and that bike is running pretty crappy right now. That thing is an aerodynamic brick and has almost 150 lbs on the 919.

So yeah thats my take on the situation. MPG is directly proportionate to where you like to keep the needle on the tach. And the more range you have the more varied it gets. 250 owners will claim anywhere from 50 to 80!

--Dan

oh and hi this is only my 2nd post!
Hi Dan and welcome to WT...you make alot of sense and I think you are right, but damn this bike is alot of fun at 5000 RPM

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post #10 of 15 Old 09-14-2008, 05:50 AM
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I get approx 20km/litre, sometimes slightly less, sometimes slightly more. The bike is stock apart from a few cosmetic changes, and although I'm pretty short I'm not that light (I'm not fat, just solid).

According to my calculations (and forgive me if I'm mistaken, I don't work well in Imperial or US measurements) this is approximately 75mpg (the gallons being US-spec gallons). That seems an awful lot compared to what you guys are getting .

I do live out in the country, the bike does mostly open-road trips and I'm not that a heavy user of the throttle. The laws here allow for immediate disqualification of anyone travelling more than 30km/h over posted speed limits. The default open/country road speed limit is 100km/h, with some freeway limits set at 110km/h. The first instance or 30km/h over period of disqualification is one month and a hefty fine, the second period or >45-60km/h over is open-ended on both counts at the courts' disgression.

As we live 15-odd kilometres from town I can't really afford to lose my license, riding to the local train station and getting there by 7am on a push bike would be a major PITA. So I take it easy...most of the time.

FWIW I used to get the same economy on my old '98 ZZR600 (the old ZX-6 to you guys), and this was heavier than the Hornet.

My first bike, a 2000 GPX250R (the Ninja 250R) was extremely frugal, I used to get 30km/l (113mpg!!!) and it seemed to go forever on a tank of fuel...just not that fast.

Mick

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post #11 of 15 Old 09-14-2008, 06:15 AM
 
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Quote:
Originally Posted by Ratmick View Post
I get approx 20km/litre, sometimes slightly less, sometimes slightly more. The bike is stock apart from a few cosmetic changes, and although I'm pretty short I'm not that light (I'm not fat, just solid).

According to my calculations (and forgive me if I'm mistaken, I don't work well in Imperial or US measurements) this is approximately 75mpg (the gallons being US-spec gallons). That seems an awful lot compared to what you guys are getting .

I do live out in the country, the bike does mostly open-road trips and I'm not that a heavy user of the throttle. The laws here allow for immediate disqualification of anyone travelling more than 30km/h over posted speed limits. The default open/country road speed limit is 100km/h, with some freeway limits set at 110km/h. The first instance or 30km/h over period of disqualification is one month and a hefty fine, the second period or >45-60km/h over is open-ended on both counts at the courts' disgression.

As we live 15-odd kilometres from town I can't really afford to lose my license, riding to the local train station and getting there by 7am on a push bike would be a major PITA. So I take it easy...most of the time.

FWIW I used to get the same economy on my old '98 ZZR600 (the old ZX-6 to you guys), and this was heavier than the Hornet.

My first bike, a 2000 GPX250R (the Ninja 250R) was extremely frugal, I used to get 30km/l (113mpg!!!) and it seemed to go forever on a tank of fuel...just not that fast.

Mick
Using your 20 km/liter...20X3.785= 75.7 km's, X.62 (back to miles)= 47 mpg (approx.)? That would put your 250 at about 70mpg.

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post #12 of 15 Old 09-14-2008, 01:44 PM
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I'm turning off the accelerator function too. It's not to increase mileage – I already get 50-55 mpg on my 55mile (one way) commute to work. I just find it a hazard when riding at low speed, such as in a parking lot, with my left hand doing something like lifting my visor, scratching, unzipping my jacket, waving at the gate guard, etc. It's just too jerky. A slight blip on the throttle and I'm two rows over with my left hand flailing in the air! The "guys" say it looks too much like I'm trying to stay on for 8 seconds!

Sure, sure, I could reduce the numbers, but I don't use it anyway so I'm going to kill it.

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post #13 of 15 Old 09-15-2008, 05:27 AM
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Quote:
Originally Posted by 1Baddaddy View Post
Using your 20 km/liter...20X3.785= 75.7 km's, X.62 (back to miles)= 47 mpg (approx.)? That would put your 250 at about 70mpg.


You don't like kilometres per gallon?

My bad

Mick

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post #14 of 15 Old 09-15-2008, 05:56 AM
 
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Originally Posted by Ratmick View Post


You don't like kilometres per gallon?

My bad

Mick
Trust me, I would LOVE to get 75mpg on my 9'er!

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post #15 of 15 Old 09-15-2008, 03:00 PM
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Quote:
Originally Posted by 1Baddaddy View Post
Using your 20 km/liter...20X3.785= 75.7 km's, X.62 (back to miles)= 47 mpg (approx.)? That would put your 250 at about 70mpg.
Or to put it in more useful terms, 20 Km/litre equals 3,179,745,898,560 microns per barrel of gasoline, or 2.11404682 × 10^-27 light years per attolitre.

I hope that clears things up.

Rob

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