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post #1 of 7 (permalink) Old 06-02-2011, 11:39 PM Thread Starter
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MPG Reality Check or Wow, Nice surprise!

This is a segway of Bret H's MPG average after ear shave post..... I wanted to include tire info....

Preface:
This is written 800 miles after doing the shave....
I really like my '06 VN750....like the way it rides, handles...even like the looks, after all, looks is what attracts us to most things, but after seeing other bikes without ears (airbox) I knew I had to make the change. I approached the Ear Shave for purely esthetic reasons...to remove the ears, but now that it's done, esthetics became an insignificant reason to tackle this job. I cannot believe the difference it has made in the performance of the bike. I barely need to choke it when starting....it just starts and idles like it was fuel injected. Acceleration, response, sound....all different (in a better way). If you goose it at 70 MPH, you better be holding on, cause she jumps outta her skin responding to the slightest touch. Bottom line: If considering an Ear Shave on the VN750, just do it. You will be glad you did. (Procedure in the link below)

Now the MPG part....
Out of the box, the VN750, after break-in period, will get approx. 48-50 MPG if you ride in moderation. Reasons for this (IMHO) is two-fold....1) factory (very) lean mixture settings and 2) conjecture has it Kawasaki geared the speedometer gearbox so it would appear you're going faster/further than actual speed/distance for safety reasons. We tend to blame the tire size but in reality, Kawasaki could have easily designed the gearbox to be accurate. We compensate for the inaccuracy of the gearbox by installing larger tires. When I installed the 110/19, my MPG dropped approx. 10% or 44-45 MPG. While disappointing, this is closer to reality. I also was closer to actual speed indicated.
Now the ear shave news...Wow, Nice surprise....
I really thought installing larger jets and adding shims would increase fuel consumption, but as it turns out, my MPG did not change after the ear shave....I still get about 44 MPG!

Summary:

Stock = 48-50 MPG
Larger tires = 44-45 MPG
Ear Shave & larger tires = 44-45 MPG

Last edited by VoIPDoc; 06-03-2011 at 09:05 AM.
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post #2 of 7 (permalink) Old 06-03-2011, 12:49 AM
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Quote:
Originally Posted by VoIP Doc View Post
This is a segway of Bret H's MPG average after ear shave..... I wanted to include tire info....

Preface:
This is written 800 miles after doing the shave....
I really like my '06 VN750....like the way it rides, handles...even like the looks, after all, looks is what attracts us to most things, but after seeing other bikes without ears (airbox) I knew I had to make the change. I approached the Ear Shave for purely esthetic reasons...to remove the ears, but now that it's done, esthetics became an insignificant reason to tackle this job. I cannot believe the difference it has made in the performance of the bike. I barely need to choke it when starting....it just starts and idles like it was fuel injected. Acceleration, response, sound....all different (in a better way). If you goose it at 70 MPH, you better be holding on, cause she jumps outta her skin responding to the slightest touch. Bottom line: If considering an Ear Shave on the VN750, just do it. You will be glad you did. (Procedure in the link below)

Now the MPG part....
Out of the box, the VN750, after break-in period will get approx. 48-50 MPG if you ride in moderation. Reasons for this (IMHO) is two-fold....1) factory (very) lean mixture settings and 2) conjecture has it Kawasaki geared the speedometer gearbox so it would appear you're going faster/further than actual speed/distance for safety reason. We tend to blame the tire size but in reality, Kawasaki could have easily designed the gearbox to be accurate.
We make up the inaccuracy of the gearbox by installing larger tires. When I installed the 110/19, my MPG dropped approx. 10% or 44-45 MPG. While disappointing, this is closer to reality. I also was closer to actual speed indicated.
Now the ear shave news...Wow, Nice surprise....
I really thought installing larger jets and adding shims would increase fuel consumption, but as it turns out, my MPG did not change after the ear shave....I still get about 44 MPG!

Summary:

Stock = 48-50 MPG
Larger tires = 44-45 MPG
Ear Shave & larger tires = 44-45 MPG
Just one correction to offer here Doc. KM pointed out to me some time ago that even though the speedometer reads 10% high with the stock size 100/90-19 tires, the ODOMETER IS QUITE ACCURATE with those same tires.

The 110/90 tires does bring the speedo very close to accurate, but makes the ODOMETER READ A BIT LOW.
Several other members have confirmed this observation.
BTW it is good to hear the earshave and rejet does not necessarily negatively affect fuel economy.

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
https://www.vn750.com/forum/11-vn750-general-discussion/9127-top-ten-items-you-would-suggest-new-owner-do-his-new-ride.html
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post #3 of 7 (permalink) Old 06-03-2011, 11:12 AM
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And I should add that a larger front tire should have no noticeable effect on fuel consumption.

I forget the difference in tire circumference between the stock rear and the wider 170/80? folks been using.

The earshave if done right, should produce more power.... Which can easily mean using LESS fuel to go the same distance. Most times it is break even deal... But it is harder to judge if one rides (accelerates) the bike differently after doing the earshave........


I also do not think Kaw made the speedo read high for safety reasons...or geared the bike inaccurately for a reason. It just worked out that way when they were done. Granted, to avoid lawsuits they do make an effort to keep the speedo readings at or a bit above actual speed....safety not the issue.

Bike engineers have a computer model that guides them when picking gearing for a bike they are to build. They punch in tire circumference and work back from there.

The speedos inaccuracy is more do to the company that supplied the unit to Kaw. Kawasakis engineers likely had nothing to do with the units internals ... just the outside design.
KM

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Last edited by Knifemaker; 06-03-2011 at 11:27 AM.
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post #4 of 7 (permalink) Old 06-03-2011, 11:55 AM
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I'd noticed the difference between the bike's speedometer and my GPS unit, which also shows MPH. Now I know it isn't just *my* bike that's off.

Thanks!

.
.
.
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post #5 of 7 (permalink) Old 06-03-2011, 04:42 PM
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Quote:
Originally Posted by VoIP Doc View Post
This is a segway of Bret H's MPG average after ear shave post..... I wanted to include tire info....

Preface:
This is written 800 miles after doing the shave....
I really like my '06 VN750....like the way it rides, handles...even like the looks, after all, looks is what attracts us to most things, but after seeing other bikes without ears (airbox) I knew I had to make the change. I approached the Ear Shave for purely esthetic reasons...to remove the ears, but now that it's done, esthetics became an insignificant reason to tackle this job. I cannot believe the difference it has made in the performance of the bike. I barely need to choke it when starting....it just starts and idles like it was fuel injected. Acceleration, response, sound....all different (in a better way). If you goose it at 70 MPH, you better be holding on, cause she jumps outta her skin responding to the slightest touch. Bottom line: If considering an Ear Shave on the VN750, just do it. You will be glad you did. (Procedure in the link below)
(It also makes R&Ring the carbs infinitely easier, saving more time, and certainly more cuss words...)
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post #6 of 7 (permalink) Old 06-03-2011, 05:31 PM
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Quote:
Originally Posted by Knifemaker View Post
And I should add that a larger front tire should have no noticeable effect on fuel consumption.

I forget the difference in tire circumference between the stock rear and the wider 170/80? folks been using. KM
It seems to me that it is more accurate to say the CALCULATION of fuel economy with the larger diameter front tire CHANGES downward.
As KM says, it can have no noticeable real effect on fuel consumption.

Regarding diameter and circumference of the rear tire, what do the numbers mean:
A 150/90-15 tire is 150 mm wide, and the sidewall height is 90% of the width.
Therefore 150 mm X 90% = a sidewall height of 135mm.

A 170/80-15 tire is 170 mm X 80% = 136 mm sidewall height.

By this calculation there is virtually no noticeable difference in rear tire diameter or circumference, so should not materially affect rpm or fuel consumption. I think an earlier calculation I made indicated a difference of only 2 or 3 tire revolutions while traveling a mile.

Gordon

1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15


TOP TEN THINGS A NEW RIDER/OWNER SHOULD DO. Click on link.
https://www.vn750.com/forum/showthread.php?t=9127
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post #7 of 7 (permalink) Old 06-03-2011, 10:59 PM
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And again my general belief here is that MPG figures go up, or down, largely based on tire pressure and the heaviness of ones wrist.

The Vulcan eats gas at a much higher rate after you eclipse 5000 rpms, and stuff like wind speed and windscreen size are always factors to add go the mix.

My 750 was bought new, ran like a top, but the way I road k doubt I averaged over 40 mpg.

I read about folks with FJRs that claim 45-48 mpg. I average 38. I bought the bike go have fun, not to save money on gas.

I ride it like I stole it and the smile on my face is worth the extra few bucks a month I pay for fuel.

KM

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