Altitude cough
Road Captain
Joined: Apr 2009
Posts: 501
Likes: 150
From: Jersey
starving for air
Has anybody ever actually taken a wideband oxygen sensor to increased elevations to actually see what happens to the AFR on a carbed bike?
This article is way more right than most people are led to believe. Why do you think your bike has less power at elevation? Well less oxygen, duh... But oxygen isn't the only component that's more rare, it's that there's just less AIR in general.
Imagine, if you will, take one big gulp of air at sea level and you inhale a specific volume of air that's 21% oxygen, 70% nitrogen, and some other stuff
Now take another gulp of air at the top of Pikes Peak. Those ratios are the same but the volume you inhaled was lower since there's less content of air in what you inhaled. It's hard to grasp, but think about outer space. What do you take a big gulp of in space? Nothing! Well as you increase in elevation here on earth you go from big gulps of air at sea level to big gulps of nothing in space. Atmospheric pressure is basically a stack of air measured in pressure at sea level that is the physical weight of a column of air that's 7 or so miles high. It's lighter at the top.
Since the CV carb (and carbs in general) all allow fuel based on how much air is going thru them, when at elevation since there's less air per gulp there will inherently less fuel to go with it regardless of how large your pistons are which keeps the ratios consistent.
This article is way more right than most people are led to believe. Why do you think your bike has less power at elevation? Well less oxygen, duh... But oxygen isn't the only component that's more rare, it's that there's just less AIR in general.
Imagine, if you will, take one big gulp of air at sea level and you inhale a specific volume of air that's 21% oxygen, 70% nitrogen, and some other stuff
Now take another gulp of air at the top of Pikes Peak. Those ratios are the same but the volume you inhaled was lower since there's less content of air in what you inhaled. It's hard to grasp, but think about outer space. What do you take a big gulp of in space? Nothing! Well as you increase in elevation here on earth you go from big gulps of air at sea level to big gulps of nothing in space. Atmospheric pressure is basically a stack of air measured in pressure at sea level that is the physical weight of a column of air that's 7 or so miles high. It's lighter at the top.
Since the CV carb (and carbs in general) all allow fuel based on how much air is going thru them, when at elevation since there's less air per gulp there will inherently less fuel to go with it regardless of how large your pistons are which keeps the ratios consistent.
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