Ok, I initially posted this in the mechanical forum but it wasn't getting many replies, so I thought to post this here, hopefully to obtain concrete answers, so that correct information is being put out in internet land.

I find myself at odds here, and hopefully someone with more knowledge can set the record straight. I usually read of stage 1's being done and going from there, that setup consisting of full exhaust, high flow A/C, and fuel management/tuner. When a person wants to change either their exhaust or A/C, they don't need to tune the ECM, reason being the O2 sensors will adjust the AFR for the change. If you do both, you will need a tune. Is this old info, because I'm starting to see people reply on the forum that a tune is now needed for any change, and even changing the tune for a stock motor should be done. And yes, I know a stock motor already runs lean courtesy of the EPA. What say you??

In searching the internet I'm seeing a lot of differing opinions about this, thanks for your replies.

Ride safe!!

 

IMHO a tune is needed even on a stock bike

IMHO HD, in order to keep the feds happy, has the bike set up to give the best results to the Feds, and not the best performance to the rider.

I want an A/F ratio of 13:1, I doubt a stock tune is at that value.

 

You answered yourself at the end of your post.
From my research the stock set up is only designed to go so far. Altitude and such.....
So already lean from the factory, you add a free flowing exhaust and let it breath , of course its going to go leaner. Can the stock system keep up with the demand?
I don't understand why you would not want to tune your bike?
I would add a tuner to a stock bike.
Just sayin.....

 

So like I said in the other thread in a response; Has anyone re-tuned a stock Harley TC motor?

It's not about me not wanting to tune my bike, I understand the tuning concept. What I'm after is that for years I was under the impression that the Harley ECM would adjust for either an exhaust change or a high flow A/C change. If you perform both, then the ECM will need to be re-tuned. I get that, but I'm starting to see people say that just doing an exhaust change the ECM needs a re-tune, or if just doing an high flow A/C change you need a re-tune.

Is that correct information? I agree, that the TC runs lean, however, I've never heard of anyone adding a tune to a stock motor. Should a stock motor be tuned? I would say yes, but does it need it?
Has anyone ever heard of someone running 100k miles on a stock motor and damage occurring only from a stock tune?? Not talking about the other issues with the motor, just the stock tuning. Thoughts??

Ride safe!

 

well you have heard of one now, I ran a PCIII on my stock motor with the only mod being a big sucker air cleaner.

 

I simplified it.

 

How so?

 

Aren't those the questions you're asking? I removed all the extraneous information in your post. Simple.

My answers are:

Has anyone re-tuned a stock Harley TC motor? Yes, I have re-turned a stock Harley TC motor.
Should a stock motor be tuned? In my opinion, yes. Others will have a different opinion.
Has anyone ever heard of someone running 100k miles on a stock motor and damage occurring only from a stock tune?? I have not.

 

For years you have been living under an illusion! 'Twas ever thus for Harley owners. When I started riding Harleys in the 1970s there were always owners who swapped mufflers, fitted slash-cuts, installed S&S carbs, etc, etc, and never bothered or succeeded in tuning the darned things to run right. Same thing continues to this day with EFI bikes. Nothing much has changed!

Like a carb, modern EFI does not automatically adjust for when we make changes to our bikes. It is however superior in adjusting for extremes of hot and cold, wet and dry, also dealing with big changes in altitude, but there has never been a built-in capability AFAIK to enable us to change away from the stock set-up. That is all part of the internet myth IMHO.

Does a stock motor need to be tuned? No. Will it benefit from being tuned? Very likely. Will a mildly modified bike run 'sort of OK' without being tuned? Quite possibly. Will it ride as well as it possibly can without being competently tuned? Definitely not!

 

Change of mufflers - no tune needed even on the milwaukee 8.
Change the A/C and you need to tune - especially with the milwaukee 8.