Louder pipes more gas?

Question

A few weeks ago I went to a Harley Davidson dealership to look at the new bikes. Mileage came up and the rep I was speaking with said that gas mileage would go down with louder pipes.

How can this be?

I'm talking about a stock 883 Evo engine pulling in the same size fuel charge as before. It's just being blown into a less baffled, perhaps bigger pipe. Is this correct or was she blowing smoke?

Answer 1

On any Harley or for that matter....Any bike you change the pipes to mass flow, you have to change the fuel mixture or the motor will run lean and burn up the engine....Even the 883.

Hense worse fuel milage. My advice is....Keep it stock, it runs best that way.  The 883 is a small motor anyway.

Answer 2

changing the exhaust will not effect the mileage or require remapping the fuel system ,if you install an aftermarket air cleaner like a K&N or the stage one screaming eagle air cleaner then you'll have to have the fuel system remapped or re-jetted depending on if it's carburated or EFI ,I have not seen any change in my 883 since I changed from the stock exhaust to custom drag pipes  

Answer 3

She was blowing smoke! An exhaust system has little or no effect on fuel mileage. Only if you ran it without the entire exhaust system would cause it to lose mileage because there wouldn't be any back pressure.

Answer 4

drag pipes just bolted on (as in no baffles) and nothing else changed WILL hurt economy AND power if that's all you did was bolt them on just to make it sound "cool"

there is benefit to power and economy of you rejet and add a high flow breather as well

i had a 1200 that 1st thing i did was drag pipes, it took alot of power away from it and it was harder on gas.  then i added a velocity stack and high flow breather and jetted the carb, it was a drastic improvement.  (then went further with cams and big bore and such, but that's a lot more than someone buying an 883 will care to dive into i would think)

Answer 5

i did a 2 stage upgrade to mine, much more power, and better gas milage. it could go either way.

Answer 6

It won't affect your mileage. I don't know what she

s smoking. Of course, it will make the bike annoying to others.  

Answer 7

The answer is not all that simple, but simply put, look at racing in any fiield. High performance is associated with the least air flow resistance. That's what high performance air filters and straight pipes acheive.

In physics if you alter some part of an equation....?

Often times changing air filters and pipes reduces the back pressure and as a result you lose compression because of the valves - this is one of the more over-looked results. Most people think that all you need to do is re-jet or re-map your system and everything will be just peachy. Spark plugs will tell you more about an engine and it's performance then anything, very often over-looked. The more I talk about this the more complicated I can make it. As an example, stuock plugs are usually a little on the cold side because the manufacture chooses this for riders who on average or more aren't looking for constant high performance and tend to lug their egines in general more often...

You can't just add striaght pipes and say it will acheive anything. It's a part of equation and disrupting it creates a new result. Jets, Mapping, Plugs, Valve Springs, Air Intake flow (filter) are all part of the equation and each must be considered and analyzed to create a desired output. Many times people look at just one thing and they are curing a symptom and disregarding the disease thsat affects them. Ultimately it boils down to what the plugs look like, that reports exactly what kind of result you're actually acheiveing ....

.02 worth of advice is exactly what it is, cheap comments produce cheap results..... study the material out there that goes indepth and look for a setup that duplicates your riding style.... that''s the answer and salesman are full of .02 advice.... trust me...

Answer 8

faster pipe flow get more power and thar for uses more gas

Answer 9

My first change was less restrictive mufflers and a DFO.

The DFO was to add more fuel to bring the mix back into balance after the muffler change.

The aftermarket air cleaner came later.

Yes, mileage went down.

Lost some low end power, too.

I modded the pipes and went to different mufflers. Brought most of it back. And she really likes the upper end now.

If you don't watch the mix, it might run lean. Lean means hot. Not good in an air-cooled motor.