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Old Sep 29, 2005 | 06:47 PM
  #1  
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Default back pressure

Alright my first post on this forum lets see if I can Get an answer. I recently purchased an 04 super glide fxdi and I was wondering if I take the baffels out of the SE II if the lack of back pressure will damage the motor I know I will need to get it re mapped.


Steve
L.I. NY

Metric to american and lovin it!!!
 
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Old Sep 29, 2005 | 07:44 PM
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Default RE: back pressure

Steve, I don't think it will ruin your engine, you will probably lose some torque at highway speeds, though. Where are you located on Long Island? I am also on L I.
 
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Old Sep 29, 2005 | 09:33 PM
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Default RE: back pressure

Both you LI guys, I'm in westchester.

Taking the baffles out will make a lot of noise but that's all. Your best bet would be to get a set of slipons and believe me when I say it will run poorly with FI with no baffles. The FI needs some backpressure to run properly.
 
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Old Sep 29, 2005 | 11:15 PM
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Default RE: back pressure

I'm in E. Yaphank NY rite by willam floyd and 495. I have the baffels out now and I do have slip ons (screamin eagles II) on the bike already. I dont have a problem with noise since I only ride for pleasure.

Steve
 
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Old Sep 30, 2005 | 12:08 AM
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Default RE: back pressure

Intruder, I have a 05 FXDI, and had the SEII slip ons also, and I thought about pulling the baffles, listen to these guys when they say not to.. if you just want more noise,like I did, get your self a set of Vance and Hines Big Shots, (staggered, shorts, longs, radius) all of these pipes will give you more performance and style.. heres a pic of my 05 with the V&H big shot staggereds... be sure to shop around for your pipes.. THIS is the link to show you the v&h pipes, but they are kinda pricey, but worth it, I got mine from the local yamahaha shop purchased, shipped and installed for about $450 or so, cant remember the exact price. Be sure also to check to see if your bike has been remaped with the current se's, I have stage 1 a/c and remap, so I didnt have to do anything but install the V&H>


KC..




 
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Old Sep 30, 2005 | 09:18 AM
  #6  
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Default RE: back pressure

sharp bike. My bike was re mapped already when they installed the exhaust so im good with that. What kind of a difference is there between the V&H and the SE II. How would you compare the two? The pipes look very sharp on your bike. do you have an after market intake also? If yes do you think I would have to re map again with a new program?


Thanx
I really appreciate the help


Metric to american and lovin it!!

PS one thing thats nice living on L.I. no problem with finding a harley dealer theres 5 all within 40 miles of me!
 
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Old Sep 30, 2005 | 11:49 AM
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Default RE: back pressure

ORIGINAL: intruder400ex

I'm in E. Yaphank NY rite by willam floyd and 495. I have the baffels out now and I do have slip ons (screamin eagles II) on the bike already. I dont have a problem with noise since I only ride for pleasure.

Steve

Steve, Not familiar with that area, I get lost everytime I go to LI Big place!

 
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Old Sep 30, 2005 | 08:35 PM
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Default RE: back pressure

Intruder400ex, I installed Vance and Hines Straight Shot HS on my bike. They sound great. I think they are a little louder than the SE slip ons. If you buy them off of the Web, you will save a lot of money. They are easy enough to install yourself. Gopartsdirect.com had some good prices. By the way, I live off of Commack Rd., Exit 52, LIE
 
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Old Sep 30, 2005 | 08:53 PM
  #9  
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Default RE: back pressure

louie everyone that lives in E northport lives off of commack rd or "bread and cheese rd".......LOL

thanx for the imput seems this forum is very helpfull

steve
 
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Old Dec 19, 2005 | 04:33 AM
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Default RE: back pressure

ORIGINAL: intruder400ex

Alright my first post on this forum lets see if I can Get an answer. I recently purchased an 04 super glide fxdi and I was wondering if I take the baffels out of the SE II if the lack of back pressure will damage the motor I know I will need to get it re mapped.


Steve
L.I. NY

Metric to american and lovin it!!!
Loss of Back Pressure and What Happens

[c]In order to achieve a theoretical optimal combustion, an engine needs 14.7 parts of oxygen by mass to 1 part of gasoline (again, by mass). This is referred to as a stochiometric (chemically correct) mixture, and is commonly referred to as a 14.7:1 mix. If an engine burns with less oxygen present (13:1, 12:1, etc...), it is said to run rich. Conversely, if the engine runs with more oxygen present (16:1, 17:1, etc...), it is said to run lean. Today's engines are designed to run at 14.7:1 for normally cruising, with rich mixtures on acceleration or warm-up, and lean mixtures while decelerating. reduction of back pressure can result in a constantly lean-burning engine and as a result burn the exaust valves.

Man that high tech talk will give you a headache. Now the simple version.

The reason that exhaust valves burn is because the engine is burning lean. Normal engines will tolerate lean burning for a little bit, but not for sustained periods of time. The reason why the engine is burning lean to begin with is that the reduction in backpressure is causing more air to be drawn into the combustion chamber than before. Unless the air fuel mixture is adjusted to compensate the engine will burn lean.

This compensation has to be done either manually, carb, or by computer, fuel injected. If the mapped range of the fuel injection can compensate that’s great. If not then the range must be varied by remapping. What remapping does is change the mixture ratio over the rpm range and to re-center the range. To effectively remap a system dyno testing might be necessary.

So can the removal of the baffles damage your engine. Yes! If the engine does not receive the compensated fuel air mixture and it constantly burns lean.

If you remap the system you should not have any problems. You might need to change the air intake to achieve the remapping.[/c]

Lee

 
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