Forgive any stupid questions here, but despite 27 years riding Harleys, EFI on them is all new to me (hell, so is final belt drive, more than 4 speeds and a button start).

I am no stranger to spannering and to archive searches, but I'm not finding these answers in a seamless order that pertains to me and a Milwaukee 8. Thanks for your input.

Let's just say that at some stage this year I am gonna remove the cat from the exhaust on my new 2019 FLTRX, which is gonna have S&S Grand National slip-ons fitted for the first ride out the dealer door.

I'm not removing the cat to add power (ain't gonna happen, I'm clear on that) or for any aural satisfaction, but purely to decrease heat.

Questions.

1/ is a retune mandatory after cat removal?

2/ is a retune to richer mix mandatory after installation of high-flow air cleaner? (I am certain the answer here is a ''yes'')

3/ Is it possible to achieve a correct/richer mix with the stock factory ECM/tuner? (I am thinking the answer here is a ''No'' because of built-in EPA appeasement)

4/ So then I absolutely mu$t upgrade to an aftermarket tuner?

5/ Considering brand-new Harleys have run lean for 30 years, will every Milwaukee 8 benefit from installing an aftermarket tuner/tune to make it run cooler and richer and assist longevity?

6/ Is there a simple PROVEN auto-tuner I can hook up using downloaded apps/maps, laptop, etc? Or am I taking my bike back to the shop for them to install a new tuner and retune?

I'm a ''get it right the first time'' guy and I am looking to have my new bike running as it should in the first year of ownership and then just putting moon miles on it without seriously touching it again. 'Thanks.

48 years on the street here , feel your pain . Only been on EFI scoots for 11 years myself ..

1) No

2) Possibly

3) No

4) Yes/No

5) Yes

6) Do not have to return to dealer .. Can of Worms , what do you want to do ? simplest is XIED or VIED , they merely enrichen some without a new map , plug in to the O2 sensors .. I use FuelPak3 (FP3) , Uses smart phone and have a bunch of maps to choose from , select model , exhaust , cams , and gives you the best map .. Or you can do as I did and say hey all I did was a de cat and they sent me the best combo for my setup , runs great .. You can run as many maps as you want , naturally one at a time .. Only draw back if you really want to play with the fuel tables , is it is for phone only ..

Others like TTS Mastertune and ThunderMax , SE tuners and Power Commanders , you can run on PC/laptop and transfer to the bike ..

You don't necessarily have to do anything on a stage 1. Its better that you do, but don't have to. THE engine will no doubt run hotter , but the exhaust where the cat was will be cooler.
I just bought a Dynojet Power Vision off Fuel Moto. They send it to you with their best fit to your mods map already installed in the unit. All you do is transfer the Software map into your bike's cpu.
Give Fuel Moto a call. Them guy will give good advice.

I had the dealer install a Stage II with a torque cam and a full V&H exhaust. I decided to use the Harley tuner to keep it warranty friendly and it was suggested to me to use HD's auto tuner module. Evidently it allows changes to more parameters than just the "regular" tuner plus I didn't have to pay for dyno time. While I'm sure I have not extracted every last bit of horsepower from the engine, it is by far the best running Harley I have ever owned. Keep it simple.....

very interesting. Is this a part that we buy, or a service dept item that only dealership techs use? I had never heard of this before. Tell me more. Thanks.

Harley's website is down until Tuesday for maintenance, so here is a link: https://www.shoputahharley.com/produ...tuning-module?

You have to get the pro street tuner and the auto tune module.....the cost of the auto tune is about the same as dyno time and it keeps the warranty. If you decide to make further changes down the road, the auto tune module should compensate for them, negating the need for more dyno runs.

You do not need to buy a tuner. find a local shop that will tune with Direct Link (see link below) this system allows them to tune your factory ECU without any piggyback unit. there is also an auto tune available for this system if you need to fine tune after a dyno tune.

If you gut the cat I'd get a tune, if you install a high flow air cleaner I'd get a tune.

Direct Link - TechnoResearch

The Harley Auto Tune module works in conjunction with the Pro Street Tuner. It changes you from 2 wire narrow band O2 sensors to 4 wire wide band O2 sensors. Wide bands have a wider window than narrow bands so they can better compensate for mods. The auto tune module will constantly monitor and adjust your tune file as you ride to give you the best possible tune at all times. You use the Pro Street Tuner with the auto tune module to put a base map in that’s very close to your combination of parts. Then, as you ride it will adjust and update the map.

Since the dealership I work at does not have a chassis dyno, I’ve installed a number of these with very good success. I’ve even used it on a bike that I installed a Stage 3 kit and 117 stroker flywheels in.

Will the HD auto tuner go outside of epa perameters , or does it just fine-tune the ST map ?

EXACTLY what I was going to ask, Gary. Thanks.

Having done a bit of research reading yesterday, I am getting the impression that even if you do shell out for these TWO (2!!) authorised H-D upgrades, (Pro Street Tuner and then Auto Tuner module), you still won't FIX the lean condition that afflicts all new Harleys for the simple reason that every H-D tuning product is limited to EPA-approved parameters in regard to the air-fuel mix.

AM I RIGHT?

Jeeze, this is getting awfully baffling for a bloke who is new to this! I have no issue with EFI whatsoever, but the tuning upgrade possibilities are bewildering.