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10-02-2012, 10:56 AM   #16
triplenickel

Joined: Jul 2008
Location: Campbell River, BC. Fantasy Island
Oddometer: 2,430
Quote:
 Originally Posted by Navin 16-50 is the cat's pajamas. +1 on the MPG, has little to no effect. The wrist controls the fuel.
I bet that would be a blast in the dirt.
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07 SE

PG007
"Up there where you eat moose-cock you must all be rockets scientists."

 10-02-2012, 11:16 AM #17 MortimerSickle Semi-Adventurer     Joined: Dec 2005 Location: Rainville, Orygun, where moss is a road hazard. Oddometer: 12,541 So, my math wasn't bad after all, when I thought my mileage improved with the 16/42? __________________ I miss round headlights. "When I was a young man, I liked to race my horse...." - G.H.W.S. 1878-1962
10-02-2012, 11:17 AM   #18
Navin

Joined: Sep 2009
Oddometer: 8,481
Quote:
 Originally Posted by triplenickel I bet that would be a EVERYWHERE.

 10-02-2012, 12:53 PM #19 tahoeacr Beastly Adventurer     Joined: Jan 2007 Location: Lake Tahoe Oddometer: 2,212 Not true. All things being equal, you will use more fuel with the 16. I have tested this extensively. Even to the point of riding slower so the rpm was the same. But, don't believe me let's look at the math. 4,000rpm equals 5.37 lbs/min of airflow. Divided by 14.7 Air/Fuel ratio equals 0.3653 lbs per minute. Multiply by 60 equals 21.92 lbs of fuel an hour. Same speed using 16 tooth would be 4,250 rpm. 4,250rpm equals 5.7lbs/min of airflow. Divide by 14.7 A/F ratio equals 0.3878 lbs per minute. By 60 minutes equals 23.27lbs of fuel an hour. All things are never equal so it will depend on how much fun your having with the new found wheelie king bike and of course your fuel map. Just went thru a high performance EFI tuning class so I had to see how much I retained.
10-02-2012, 01:22 PM   #20
DrKayak
Retro Rider

Joined: Mar 2010
Location: Shingle Springs CA
Oddometer: 808
Quote:
 Originally Posted by tahoeacr Not true. All things being equal, you will use more fuel with the 16. I have tested this extensively. Even to the point of riding slower so the rpm was the same. But, don't believe me let's look at the math..
Yea, and I know people who have extensively tested on my FZ1 and my Diesel truck with the same results.

But more than likely it's all just "a reflection of the posters misunderstanding of how motors work."

10-02-2012, 03:26 PM   #21
Sporting Wood
I <3 Energizer Bunny

Joined: Oct 2011
Location: Horneytown, NC
Oddometer: 896
Quote:
 Originally Posted by tahoeacr Not true. All things being equal... All things are never equal.
Quote:
 Originally Posted by DrKayak Yea, and I know people who have extensively tested on my FZ1 and my Diesel truck with the same results. But more than likely it's all just "a reflection of the posters misunderstanding of how motors work."

You guys are pretty funny.

10-02-2012, 03:31 PM   #22
triplenickel

Joined: Jul 2008
Location: Campbell River, BC. Fantasy Island
Oddometer: 2,430
Quote:
 Originally Posted by tahoeacr Not true. All things being equal, you will use more fuel with the 16. I have tested this extensively. Even to the point of riding slower so the rpm was the same. But, don't believe me let's look at the math. 4,000rpm equals 5.37 lbs/min of airflow. Divided by 14.7 Air/Fuel ratio equals 0.3653 lbs per minute. Multiply by 60 equals 21.92 lbs of fuel an hour. Same speed using 16 tooth would be 4,250 rpm. 4,250rpm equals 5.7lbs/min of airflow. Divide by 14.7 A/F ratio equals 0.3878 lbs per minute. By 60 minutes equals 23.27lbs of fuel an hour. All things are never equal so it will depend on how much fun your having with the new found wheelie king bike and of course your fuel map. Just went thru a high performance EFI tuning class so I had to see how much I retained.

How close to 14.7 do we stay as we change carb circuits I wonder? Also what would be your speed @ 4000rpm in sixth? I want to take the numbers one step further for fun and see what an extra .22 gallons per hour would be on paper.
__________________
07 SE

PG007
"Up there where you eat moose-cock you must all be rockets scientists."

 10-02-2012, 03:58 PM #23 MortimerSickle Semi-Adventurer     Joined: Dec 2005 Location: Rainville, Orygun, where moss is a road hazard. Oddometer: 12,541 Apparently, more factors are involved here than I even know how to find out. I use only two factors: how many miles I go, and how much gas I burn in that distance. __________________ I miss round headlights. "When I was a young man, I liked to race my horse...." - G.H.W.S. 1878-1962
10-02-2012, 05:00 PM   #24
lost in hood river

Joined: Feb 2008
Location: Hood River, Or.
Oddometer: 1,943
Quote:
 Originally Posted by MortimerSickle Apparently, more factors are involved here than I even know how to find out. I use only two factors: how many miles I go, and how much gas I burn in that distance.
That's sooo old school
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It's not an adventure until you cross a bridge , 2011 WR250, 2015 ktm 690r

 10-02-2012, 05:37 PM #25 Mttodd Adventurer   Joined: Jun 2011 Location: Billings, Mt Oddometer: 37 Just changed back from 16/45 to 17/45. 16/45 on my 950 yielded about 5800 rpm, 6th gear 80mph. about 1500 rpm over stock 17/42. Felt like a little too much on the highway, and dropped the fuel range. 17/45 yielded about 5000 rpm at 80 mph. The 17/45 is very close to the 16/42 ratio with the ability to have short gears with very little effort. One thing that surprised me is that the bike feels faster with the 17/45 setup over the 16/45. Seems like the torque output was almost wasted on the shorter gearing, just wound out super fast, shift shift shift. Where the slightly longer gearing makes more speed. Should have timed some quarter mile runs. Just a seat of the pants feeling, FWIW.
10-02-2012, 05:59 PM   #26
MortimerSickle

Joined: Dec 2005
Location: Rainville, Orygun, where moss is a road hazard.
Oddometer: 12,541
Quote:
 Originally Posted by Mttodd ...One thing that surprised me is that the bike feels faster with the 17/45 setup over the 16/45. ...
That is something I found out in making gearing changes for drag racing. With a lower ratio you don't feel the effect of the torque as much, and if you are not hard on it, it can feel a little anemic. But, with the lower ratio, your E.T. will be quicker.

However, neither speed, nor acceleration were reasons for my going to the lower ratio on the KTM. Ease of starting out on an incline, and the ability to go slower than 10 mph were what I was after. That I have been fooled into thinking my mileage did not suffer is just a bonus.
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"When I was a young man, I liked to race my horse...." -
G.H.W.S. 1878-1962

 10-04-2012, 04:55 PM #27 rokklym one man wolfpack     Joined: Nov 2004 Location: Westby Wisconsin Oddometer: 4,455 I got the deed done tonight! Finally have the new chain and sprockets on and I like it! Only got to put maybe 15 miles on but it feels good! Might not be the greatest gearing for a cross country trip but should work well for me. I got mine from the Sprocket Center I think, and they had great prices! __________________ Check out the Blog! MotoGraphic MotoGraphic Tumblr Chad Berger DR650, KTM 990 Adventure R Lone Wolf Expeditions

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