Please correct me if I am wrong, the purpose of the ECU is to control the fuel/air ratio, to provide the correct amount of air throughout the fuel supply range, (accelerator position from closed to full open) the optimum from what I remember is somewhere around 13%, the more fuel you require by opening the throttle the more air you require to obtain the ultimate mix and therefore the best performance, so it does not matter what you do with the AC this only becomes a restriction at the very top end of the scale, and only if the air required is beyond the capacity of the Filter itself, under normal operating conditions this would not be noticeable whether or not you had an AC fitted or not. The computer will do its job, The second part, the exhausts, they need to provide a certain back pressure and suction to remove spent fumes to allow the fuel/air mixture to enter the cylinder at optimum, so the design for exhausts is very important, they also have certain resonances in them which can cause back flows and prevent the gasses from escaping, this is the reason for balance lines between the two exhausts, to try and prevent a back flow, but again the exhaust should not cause the mixture to change, the O2 sensors provide feed back to the computer as to how efficient the ignition is and it should compensate for that, so to be honest I don’t see what effect this all has, if you buy after market exhausts normally they have been designed to provide the flow and back pressures required and for me re mapping should not be required, the problem as I see it is that to meet the stringent emissions laws Harley have to run their engines lean, this wont change with changing the filter or the exhaust, but what the dealers do because the bike is no longer standard and they cant be held accountable for the emissions is recalibrate the ECU so the mixture is at its optimum, and the motor no longer runs lean, thus providing what they were designed to do in the first place, this altimately gives a better ride and cooler opperating temperature,
Your comments please,

 

The new bikes with the o2 sensors have narrow band sensors and will adjust to a certian point. Its too bad H/D didnt go with the wide band sensors as that would adjust thru a wider range but that said you can for sure add slipons and not remap and possibly the air filter also. This remapping stuff came with the earlier computer controlled bikes like my 06 classic with no o2 sensors . You remapped cause you leaned it out more and didnt want to run too lean and possibly melting it down. I just talked to the guy that dynoed my 06 the other day and i had a few questions for him and the main one was how come the map on my pcIII has all - numbers. Yup he took fuel out and never added any and it runs great lots of power and torque it doesnt run hot and gets 42-45 mpg? He told me he has seen a few twin cam 88 motors that were really fat mid range and on up and mine was so thats the reason for the - numbers... Ok good answer i went on my way. But again all this remapping started with bikes without o2 sensors but as you stated these things all run lean to meet the regs and from all our schooling thru the years it appears to us that lean is too lean. Maybe,,,,, maybe not..
This could go into several pages id bet
Dave

 

What complicates tunning a HD is the uncontrolled combustion chamber temperatures. Being air cooled, richening the AF is a simple solution to cool and reduce pre ignition with head temps the can go well over 300*. If HD motors were liquid cooled and maintained a consistent lower combustion chamber temp, We would be able to lean mixtures and advance the timing and get well over 50 MPG. Part of owning a Harley is putting up with the alleged problems and putting our personal touches on them. We need to rely on the tuner knowing what he is doing in regards to performance and economy and tuning the bike correctly which will leave a lot of HD owners complaining about heat. I don't mind the heat!

 

You change the airflow (increase OR decrease) in the engine beyond a certain point = you need to remap. Just that simple.

FWIW if I changed anything on my bike I would at least get the dealer stage1 download.

BTW, Mastertune is coming out with a really cool race tuner that you can tune your bike without a dyno fairly easily. (Mastertune made the first generation SERT)

 

Fixed it. You were saying it backward.