HI All, A little help with an issue? I have had a number of big twins ans sportster over the years and have customize all of them myself! I bought a 09 nightsters about a month ago and made plans for things that needed changing, Exhausts, Bars, Seat, Air filter etc! So I changed the exhausts and now the bike is back at Harley for a New rear cycinder?????, So my questions are following (1) Are Harley making the new bike this fragile? compired to older models (2) Do you have to install Fuel-pak, Bigger air filter just to change the stock exhaust? and what would happen if I removed the baffles from the stock exhausts and added a Screamin eagle heavy breather? Any help would be great! Thnx Niall

 

(1) No, it isn't "fragile." HDs are very well-built of heavy-duty components, and with a reasonable amount of care and caution will last a lifetime. (2) Yes, you MUST install a fuel-pak or race tuner of some sort when replacing the full exhaust. You would have to do this with any fuel-injected bike of any brand. They all have to run so lean now for EPA that if you make them breathe better, they get too lean, and you start burning pistons and the like. If you were to remove the stock exhaust baffles and add a SE Heavy Breather, you would melt your rear cylinder again. Do it right, get a tuner. You'll save money in the long run, make more power, and be much happier.

 

#2 is wrong. Way wrong.

Do I need to remap my ECM when installing exhaust and air cleaner upgrades to my 07 and later Harley?
NO, you do not have to do anything. You can put the mufflers/air cleaner upgrades and ride the bike without having to worry about the engine

The simple truth is the 07 and later HD's will run just fine with exhaust/air cleaner upgrades and you do not have to do anything to the ECM at all. Closed loop EFI operation uses feedback from the O2 sensor to maintain a constant AFR, even if changes are made to the exhaust and air cleaner.

The amount of information about what has to be done '07 and later Harley when installing exhaust/air cleaner upgrades has been the subject of FUD (Fear, Uncertainty and Doubt). Riders, Dealerships, Parts Suppliers and Aftermarket Shops have presented old-wives tales, bad technical information, mis-information and in some cases, just plain flat lied about the capabilities of the Delphi closed loop ECMs on these bikes.

Most people hold on to their old ideas about what was required for the early EFI ECM's. Shops and Dealerships never bothered to learn new the new technology. Marketing information did nothing to dispel the differences between the old and new bikes. Sales staff did not know the difference or mis-represented what was required on the new bikes.

There is more independent proof that you do not need to remap the HD EFI when installing mufflers. The March 2009 (page 66) CycleWorld dyno tested a set of slip-on mufflers on an '09 FLH, getting 5% more HP and 9% more torque on a "bone-stock, including EFI mapping" bike. Cycle World is not known as a big Harley cheerleader, so it would be a reasonable assumption that they are not going to do any special favors for MOCO.

The CW information is right in line with what HD published in the Fall 2006 Enthusiast Magazine showing a 3% HP and 7% torque increase with slightly more restrictive mufflers and air cleaner kit. American Iron Magazine has also published similar articles about "no remap" upgrades involving exhaust/air cleaner changes.

How much information has to be presented to Harley Riders that remapping of the ECM is not required for exhaust/air cleaner upgrades for closed loop bikes? When it can be shown that much of the "gain" in power for bikes remapped with expensive tuning software and piggyback controllers would have occurred without spending $400-$1000, riders need to start thinking about what they are really trying to accomplish on their bikes rather than blindly following the "you must remap just to add exhaust/ac" advice that has been discredited.

American Iron Magazine routinely presents exhaust/air cleaner upgrades on 2007>later bikes without doing any ECM remap's. As one of the premier H-D magazines, you must assume their technical staff has some knowledge about how the Delphi closed loop ECM works. So you can be fairly sure that when AIM publishes a dyno sheet with improved power and the bike did not have an ECM remap, that the information is accurate.

 

Slip-ons are not a full exhaust system, which is what the OP asked about. Slip-ons are fine with no change to the computer. A full exhaust WILL make your engine excessively lean, as will a better-breathing intake. Both will go way beyond what the ECM can compensate for.

Fear, uncertainty, doubt... WTF? Try science, physics, and electronics. Even if the "FUD" theory were correct (it isn't, btw), isn't a computer upgrade cheap insurance? One rebuild pays for the computer and dynamometer time...

Of course, you're more than welcome to take bad advice, and just keep rebuilding your engine.

 

HD themself has published papers that show an increase in performance when adding fuel mgmt, etc. However, they also show an smaller increase with NO WARNING about aftermarket intakes and full exhaust systems with NO ECM mapping whatsoever.

 

My intent here is to learn, not to flame so I'll expose a little ignorance in the hope that someone more knowledgable will respond. I had though as the previous poster that in a closed loop control system the ECU would simply adjust the fuel mixture based on the current conditions. But as I read more I think that the system really isn't all that controlled. What I thought I had read was that the ECU in our beloved bikes WRT to the EFI system is really just a control map based on throttle position and engine temperature.
Now these maps are built with a known constant (as the previous mentioned two are variables) and that's the air flow. As you change the air cleaner with something that allows more air into the system, the maps will be off. In other words, the ECU is NOT looking at the air/fuel ratio as it mixes, rather simply dumping a preset amount of fuel based on a few condtions (throttle position and engine temp). If you allow more air in and keep the factory preset maps, you'll be running too lean (fuel/air ratio is screwed up since you're letting more air in).
The purpose of those highly expensive map units is to remap the fuel ratios at your throttle and engine temp based on the new amount of air flowing in. Some are tuners that allow for adjustments at dyno time, some are dialed in based on engine, exhaust, air cleaner, etc.
That's my understanding. If I'm wrong someone else please chime in and correct me.
I'm learning as I go.

 

When I installed my SE mufflers and breather, I noticed that the bike was running much leaner. I went and had it remapped and the scoot runs like a champ. Everyone that I have talked to has said to either use a tuner or at least remap when doing these types of mods. Best of luck OP.

 

You are 100% correct!

Being from a racing background I would also like to add that engines always run the best just before they blow up (melt down). Lean is good for making power (hence the gains in power they are seeing on the dyno's) but not good for reliability. If you run it a little richer your motor will run cooler and last longer. Fuel mgt. systems can run richer or leaner at different throttle positions. Thats how they maintain mpg while increasing performance.
Only a Dyno and a drag strip can tell the small difference in power.. If thats what a person is looking for is numbers, good for them. If a person wants to enjoy their bike for a long time then fuel mgt. system is the way to go. (just my 2 cents)

 

Agreed and correct. Some people for one reason or another though just like to hand money to HD for no reason at all.........LOL!

 

LOL! Science, physics, and electronics......coming from the guy that said the licks bag would mess up your ride......ummmm....yeah, ok.