I have a 2011 Fatboy only engine type mod's are:

High Five MACH II Air Cleaner
Slip on pipes (I believe KhromeWerks), I will be changing these in the near future to V&H Big Raduis 2-1.

My Indy said up front that it "might" need a tuner (when the installed the air cleaner) but after installing and test ride they indicated I did not need it. Supposedly, the O2 sensor provides the info and the ECM (not sure if this is right...whatever controls the air/fuel mixture) and it made the necessary corrections.

I keep reading everywhere that if you change exhaust and breather you need something to correct the change in air flow.

Bike runs fine, there is no lull or lag. Do I need to worry? I understand that when I change the pipes again, I run the risk of needing one at that time. My question is, am I in any immediate danger of doing harm?

 

The ECM will retard the timing to prevent further detonation if the mixture is too lean, so you should be fine.

But I would get a tuner for that new exhaust.

 

^^yeah that

 

Look at the Power Vision!! Buy from FuelMoto. Check out my Photo album for pics of it installed on handlebars.

 

Get the thunder automax,,big$$$$ but it will tune your ride in any and al l climates ,hot.cold or high altitude.check dr vtwin drew has the best price i have seen.i have a sert but soon as i can the automax will be on it..check zippers sight

 

You are confusing detonation with pre-ignition. They are 2 completely different things caused by completely different contributing factors.

What you are referring to is the spark knock sensor. Spark knock is another term for pre-ignition. The contributing factors for pre-ignition are high compression, advanced timing and low octane fuel (high temps also make it worse). Lean mixture is not the cause of pre-ignition. Lean fuel mixture is the main contributing factor for detonation.

When the O2 sensors detect a lean condition, the ECM adds fuel to the mixture, it doesn't retard the timing (that would be the knock sensor). That's how the ECM adjusts the mixture for elevation and temperature changes. If the mixture becomes too lean (out of range), it is beyond the ability of the system to compensate.

Also, pre-ignition occurs at low RPM under load, while detonation occurs at higher RPM.