I watch a lot of Dwayne and Kevin's videos myself. They know their stuff. I have a 2019 Ultra Limited 114. The first thing I did was get rid of the HD slipons for a set of S&S. Other than a slight change in dB they had no affect on the way it ran. Awhile later, I put a Ventilator on it, which seemed to make it feel a bit more responsive off-idle. Other than that the characteristics were the same. No popping, no backfiring, business as usual. I ran it that way until I got the cam and dyno, which baseline showed it still a tad rich and after the cam I had to upgrade the Ventilator filter to the fatter Arlen Ness filter becauae it still wanted more. From first hand experience, I find the M8 to be plenty rich to support slipons and air cleaner. Either that or it adjusts, as some have said. My Twin Cam on the other hand could never be done like that. My personal belief is either engine could benefit from a real tune on a dyno, whether you do anything to it or not.

 

Curious why the last of twin cams were not as strictly leaned out by epa? What's the difference?

I have wondered if worth tuning stock bike. My 2015 I left stock, because I really like the stereo on it.

I am curious why someone would change air cleaner and not tune. The pipes they do for noise.

It's an age old debate since forums started, do you need to tune for just slip ones. Probably the second thread, followed by which oil

 

The M-8 has dual spark plugs, 4 valve heads, a more efficient combustion chamber, and I imagine the ports flow at higher velocity and mix the air and fuel better than the twin cam engine, so comparing the two engines is not the best way to find an answer for the OP's question. A few dyno runs before and after modifications using an exhaust gas analyzer is a more accurate point of reference.

 

Interesting thread,I have a stock 2019 107 Electra Glide and a full S&S exhaust system with Grand National mufflers I'm planning to install.
Everything else is stock except a K&N air filter in the stock airbox.
It sounds like I may be able to ad the exhaust without a tune.
Having my local indy do a 30K service soon so I guess I'll have him put the exhaust on and see how she runs.

 

Why pre 2014 date?
I also realize M8 s are different,but is EPA? Mostly care about twin cams though


Also why add air? I get noise.

 

An engine is basically an air pump, Rounders. With less restrictions to get more air/fuel at the proper ratio in and exhaust out, the engine makes more power. The exhaust system needs to be tuned for the engine and any modifications it has. The wrong exhaust system will severely hamper performance. More noise doesn't automatically mean more power. That's why shops sell performance packages of parts that have been proven to work together. Randomly throwing different parts on a bike results in poor performance.

 

That was not my question,I got an idea how it works. My question was why pre 2014, and why do an air cleaner.

As I said I some just change pipes people just want noise. I didn't say if I agree with not tuning

So please spare me the air pump lecture.

I never said there was an advantage to just changing pipes, other than some just noise. I never have just changed pipes

 

because the ac change is strictly cosmetic. the stock ac (on m8) is already a 'free flowing' ac, so technically not increasing the amount of airflow into the engine, ergo no tune needed.

 

My 107 M8 with air kit and slip on muffler, no cat. I have never had a tune added, at 29,000 miles, runs perfect. If I did a cam, then I definitely would.

 

Just adding a little info on this subject. Concerning EFI bikes, the ECM will adjust the fuel trim to compensate for some modifications up to the point the fuel tables run outside the calibrated parameters. At this point a DTC will set and the ECM will go into open loop (default cal not looking at O2). A tune will refine the spark curve, fuel tables, and enrichment (accelerator pump if you will) to get the best performance out of your modifications.