New Pipe Question

I have a 2004 Road King Classic, I just put new screamin Eagle slip on mufflers on yesterday. The parts guy at my HD dealer told me I did not need to do the stage 1 kit or update the ECM software right now, (or never), if I did not want to. Am I running a risk of hurting the engine without the ECM download?

Thanks for any help.

Holey Pistons!!!

That's why the guy at the dealer is in parts and not a mechanic! As you improve the breathing of your engine, the mixture becomes leaner. A lean mixture can cause lots of damage to your engine including burning holes in the piston. The engine will also run hotter which decreases engine life. Put on the Scraming Eagle Air Cleaner and have them do a stage 1 download. You also know which parts guy it is not safe to ask technical questions.

vybr8r,

You just confused me. I have installed SE slip-ons on three Harleys in the last three years and each time the bike ran richer. How does opening the exhaust without giving any more air to the intake make a bike leaner? How can one exhale more than is inhaled?

I'm not disputing your statement, only trying to learn. This whole breathing issue has me exhausted (pardon the pun).

You will be fine without a download. You need to worry about that more when you mess with the intake. If you were to also do a new air filter, cam or head mods or anything more extreme then you'll want to re-map it. With only an exhaust change you will not do any damage. It's the intake that changes the air-fuel ratios dramatically to the point of causing damage without the downloads.

Lean on me

Sledmedic,

Sorry, I have to disagree with part of your logic. While you are correct in that the intake restricts airflow and changing mufflers does not have a tremendous effect, it does change the flow to a degree. Since you are decreasing back pressure, the engine will breathe a little better as the total flow capacity of the air cleaner is not reached stock. On a carbed bike this is not a real issue and usually any lean condition can be adjusted out with a tweak to the idle mixture since it is lean to begin with. However, the EFI bikes are a whole different animal. The Magnetto Morelli EFI bikes were border line lean to begin with and many rear jugs were fried to prove it. Altering air flow of any sort is likely to toast the top end real quick. The Delphi EFI is a different animal in that they do have the MAP or Mass Air Pressure sensor that will sense the increase in flow and the EFI does have a limited range of compensation. However, in our experience you have about a 50% chance that you will run lean. With SE/SEII mufflers you will most likely be fine as they are plugged up as all get out anyway. Put a set of Hookers or V&H on there and you are much more likely to be borderline lean.

I would listen to what the bike is telling you. Is it running hotter? Ping, rattle or have more lean pop on decelleration? Do your shiny new mufflers show a gold tint just after the header clamp? If so, you will need to do something to adjust the fuel curve. There are many choices from the Stage I ECU flash to the Harley Race Tuner to the DFO or Digital Fuel Optimizer or the Power Commander and others. Any of these will address the problem.

The keys are to plan ahead for what future mods you might make. If you are sticking to Stage I, add a free flowing filter and have the Stage I ECU flash installed or use any one of trhe other products. If you think you may add a cam or go to a 95" kit etc, choose a tuner that allows you to adjust the mixture and timing. There is no real need to have the ECU flashed unless you want the higher RPM limit. The Power Commander or the Harley Race Tuner will allow full control of timing and fuel.

Long ago, we took a bone stock FXR and put the original SE mufflers on it after getting baseline runs. The HP gain with a stock aircleaner was about 2 HP so we know there is more air flow. After swiss cheesing the backing plate and adding a K&N we gained another 4-6 HP. Adding a SE air cleaner netted an additional couple HP. The experiments showed the changes in flow from stock to mufflers etc. It also demonstrated that the amount of power you gain with just mufflers is minimal yet still required minor carb adjustment. At that point, it just makes more sense to add a free flow air cleaner and get the mixture right and gain the free horse power.

Great info CD...and yes, I stand corrected. I was also assuming the compensation with the EFI and just switching the mufflers over. It makes sense though....when I posted I seemed to have forgotten that it took a week of re-jetting the carb on my old shovel to get it right after I put drags on it. I sure don't miss that fussy carb. Starting that thing was like a NASA launch sequence....Petcock, Enrichener, Two priming kicks, Turn the key, Two throttle blips, then the final couple of kicks...any other combo or sequence and it was a nightmare to get her going!!

I'm posting a follow-up to my previous post. I just bought a 2004 flhtcui a month ago and put the SE slip-ons without the breather upgrade or re-map. I just got home from an 8 day, 4550 mile trip out west and up to Montana and Wyoming. I rate the trip as the most miserable ever of many cross-country ventures. Why? The rear jug ran so ****ed hot I had to stand up to keep from burning the back of my thighs every time I climbed a steep hill. Traffic jams were torture. Stopped at three Harley dealers who all said that adding the slip-ons couldn't possibly cause the bike to run hotter.

I find the comments posted by CD to be very interesting. I also believe what he says, based on this experience of mine. It's a real shame that Harley techs who install these components every day aren't savvy enough to identify my problem. I was willing to do whatever they suggested. They just blamed the hot running engine on the high ambient temperatures. But, I experienced the same overheating when the temp was 80 F.

Thanks CD. Any chance that this extra lean condition is also responsible for the pipes being so obnoxiously loud (like a Snapper lawn mower with the muffler burned out)? All my previous SE pipes had a deep throaty rumble like I prefer. These are just loud.

Power Commander

CD mentioned the Power Commander. My boyfriend got his new pipes and Power Commander yesterday. Despite the poor technical writing in the instructions, I managed to download the right map and got it installed. The whole process of installing the unit on the bike, the software on my laptop and doing the download took less than an hour (he installing the unit and me handling the computer end of things). The download itself was about 15 seconds. They charge you $140 at a dealership! I'm thinking about going into business...

Anyway, he's very happy with the way it runs and it'll only take one more download to pay for the Power Commander. It makes it much easier to make changes when you can take care of the downloads yourself.

Hotone,

I've heard many success stories of people installing and mapping the Power Commander. I'm tempted to buy and use the piece myself. But, as I understand it, there is a significant difference between using a Power Commander and doing a ECM re-calibration. In fact, some techs I've talked to advise doing both. I believe that the Power Commander does not re-program the ECM at all but only alters the data which is fed to it (kind of like lying to it to achieve the desired outcome).

CD, maybe since the subject has been raised in this forum, you could briefly explain the role of the ECM and the Power Commander to us. When you get time, of course.

Wow! Thats a lot of info! Keep in mind this is my first H.D.
2004 Softail Standard EFI
All I have done is knock the baffles out of the factory tips at this point. The only reason I done that is to gain a little more sound.
I do plan on certain upgrades but at this point am I risking damaging anything without any sort of electronic upgrades ie. stage I, DFO, Powercommander etc.?
Thanks!
Don

Nature of the beast?

Long story kinda short 03 Softtail. Stage 1 w/V&H 2 into 1 pipes. 6 months ran great...started popping when I let go of the throttle. Dealer states normal "Nature of the beast for 2 into 1 pipes" I asked well for 6 months it was running abnormal? He stated they ran it on the computer and it will not hurt anything.