Screamin Eagle vs Vance and Hines
Tourer
Joined: May 2012
Posts: 262
Likes: 1
From: New Jersey
Well, there was a major innovation for Harley bikes in about 2007 (depending on the model) with the introduction of O2 sensors and closed-loop operation. Of course, other bikes and cars had this for years before but that's HD for you.
What the O2 sensors do for you is monitor the current tune and conditions and make on-the-fly changes to your air/fuel ratio to achieve a good balance between MPG and performance at lower RPMs (<4500) and lower loads (<90kPa) i.e. where you do 90%+ of your riding.
Unfortunately the piggy-back nature of the PowerCommander 3 and 5 means that they can't work with O2 sensors or they would tend to undo the fuel changes the PC is making. So, to use a PC you have to disable the O2 sensors. This is because of the limitation of the PC system, not because its a good thing to do. In fact its a poor thing to do because you have just set the technology clock back 10-20 years for your bike.
"Does this matter?" Well, yes. You have to hope that the canned or tuned map in the PC is always going to be good, relying that outside conditions (air pressure and temp) are never going to vary. Of course they do and your bike can no longer self-adjust for them.
"No, really, does this matter?" The bike will likely run fine and you could have a fair tune. However, it could be so much better. You are likely running richer than necessary or leaner than optimal at different times. In other words, things could be better.
Dynojet recognise this limitation of their product and for even more money you can bolt an O2 sensor back in with the PC5. So, you are spending more money to re-enable something you disabled because of a limitation of the PC! Doh!
PowerCommanders get pushed as a tuning solution because they are popular with tuners. They don't have to understand the bike at all, it could be a Harley or a Ducati, they can tune it the same.
People who understand Harleys and how to tune them use a tuning solution that isn't a piggy-back system and that works with the native tuning tables of the ECU to produce a good tune without have to disable parts of the engine management system. Tuners like this are SEPST, TTS and Power Vision.
What the O2 sensors do for you is monitor the current tune and conditions and make on-the-fly changes to your air/fuel ratio to achieve a good balance between MPG and performance at lower RPMs (<4500) and lower loads (<90kPa) i.e. where you do 90%+ of your riding.
Unfortunately the piggy-back nature of the PowerCommander 3 and 5 means that they can't work with O2 sensors or they would tend to undo the fuel changes the PC is making. So, to use a PC you have to disable the O2 sensors. This is because of the limitation of the PC system, not because its a good thing to do. In fact its a poor thing to do because you have just set the technology clock back 10-20 years for your bike.
"Does this matter?" Well, yes. You have to hope that the canned or tuned map in the PC is always going to be good, relying that outside conditions (air pressure and temp) are never going to vary. Of course they do and your bike can no longer self-adjust for them.
"No, really, does this matter?" The bike will likely run fine and you could have a fair tune. However, it could be so much better. You are likely running richer than necessary or leaner than optimal at different times. In other words, things could be better.
Dynojet recognise this limitation of their product and for even more money you can bolt an O2 sensor back in with the PC5. So, you are spending more money to re-enable something you disabled because of a limitation of the PC! Doh!
PowerCommanders get pushed as a tuning solution because they are popular with tuners. They don't have to understand the bike at all, it could be a Harley or a Ducati, they can tune it the same.
People who understand Harleys and how to tune them use a tuning solution that isn't a piggy-back system and that works with the native tuning tables of the ECU to produce a good tune without have to disable parts of the engine management system. Tuners like this are SEPST, TTS and Power Vision.
Road Warrior
Joined: Apr 2010
Posts: 1,739
Likes: 10
From: Suffolk, England
Just need to convince my wife, kids and boss and I'm sorted 
. Seriously though, I am allowed an opinion, right?
Seasoned HDF Member
Joined: Oct 2010
Posts: 12,227
Likes: 7,803
From: Along the shoreline in SW FL
I go by the lines of the pipes first, rather than sound first.....I love fatter slash down pipes.
I won't get V&H pipes ...pretty much because then I'll just look like everyone else. I don't need the "Hey look at me" drawing sound of them.
I like my SE pipes...they're mellow as I roll through town...and when I'm out on the open road, when I roll my right wrist they come to life when I want 'em to.
I won't get V&H pipes ...pretty much because then I'll just look like everyone else. I don't need the "Hey look at me" drawing sound of them.
I like my SE pipes...they're mellow as I roll through town...and when I'm out on the open road, when I roll my right wrist they come to life when I want 'em to.
Road Master
Joined: Mar 2009
Posts: 962
Likes: 0
From: .....
Thanks! 
Quiet you! 
About 2 seconds after I snapped that pic, a big *** black bear ran behind me; spilled my coffee. I live on the edge of the woods in central Wisconsin and these damn bears are getting out of hand here. There needs to be a round up and send them back to Soldier Field where they belong.
About 2 seconds after I snapped that pic, a big *** black bear ran behind me; spilled my coffee. I live on the edge of the woods in central Wisconsin and these damn bears are getting out of hand here. There needs to be a round up and send them back to Soldier Field where they belong.
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Seasoned HDF Member
Joined: Oct 2010
Posts: 12,227
Likes: 7,803
From: Along the shoreline in SW FL
A good lookin' bike is a good lookin' bike.
Ultimate HDF Member
Joined: Dec 2006
Posts: 5,878
Likes: 17
From: The Desert SouthWest
There are some reasons to consider SE pipes...
1. They are legal. You won't get ticketed with SE pipes.
2. If you don't like stupid loud then they are a nicer sound than stock. An excellent choice then if you do a lot of miles rather than posing around town frightening children.
3. You won't damage your hearing.
4. If you choose a SEPST as your tuner then the canned maps will work and can be put on, potentially saving you having to dyno tune.
5. Some V&H pipes (Short *****, Big Radius) produce less power for stage 1 than the SE slipons.
But I know that some folks' priority is 1. noise and 2. looks, with performance a low third. So you make the choice.
1. They are legal. You won't get ticketed with SE pipes.
2. If you don't like stupid loud then they are a nicer sound than stock. An excellent choice then if you do a lot of miles rather than posing around town frightening children.
3. You won't damage your hearing.
4. If you choose a SEPST as your tuner then the canned maps will work and can be put on, potentially saving you having to dyno tune.
5. Some V&H pipes (Short *****, Big Radius) produce less power for stage 1 than the SE slipons.
But I know that some folks' priority is 1. noise and 2. looks, with performance a low third. So you make the choice.