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Discussion Starter #1
Hi, I have been researching and need some help before I attack this situation.
I debaffled my exhaust and love the way it sounds, but I understand that I might have lost back pressure. I read somewhere that a bolt inside the pipe will help getting back some of the BP.
Can someone guide me thru this?
thanks in advance.
 

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Hi, I have been researching and need some help before I attack this situation.
I debaffled my exhaust and love the way it sounds, but I understand that I might have lost back pressure. I read somewhere that a bolt inside the pipe will help getting back some of the BP.
Can someone guide me thru this?
thanks in advance.
I'ts a wives tale. 4 stroke engines don't require the back pressure like 1990's 2 strokes did. You did open your exhaust up.. so more air out, more air in... more air more fuel. I have been running debaffled exhaust for 5 years with a VFC and Lloydz intake filter. No issues. The head pipe on XC and XR have the cats in the head pipe.

People have added all kinds of things to their debaffled to make it sound different or stop backfiring. A good tune stops the backfiring. Adding items or baffles will just change the note and disrupt the flow.
 

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Discussion Starter #3
ok, so I dont have to worry about messing anything up for lack of back pressure then?
A fuel tuner, timing wheel and air filter are my next mods. I accept suggestions from more experienced members on this matter....

Also was debating about the Air Valve, but I read too many posts that suggests that is not worth it.

Thanks again for the quick response.
 

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If you plan on doing cams the I would skip the timing wheel and get the ECU flashed or get it tuned with the Maximus tuner. You can set the timing better through the ECU and skip having to have the timing wheel and PCV. You get a smoother power band from what I have seen and you have no addon parts that could fail. You keep the Maximus tuner with you VIN in it and your tuned map so if you ever have ECU problems in the future you can reinstall the map yourself.

I see you're in Florida, they are having their annual Spring Horsepower weekend in Southern Maryland in May. Hosted by one of the top 5 Victory guys, arguably the best Victory tuner out there. Installs, dynos, deals and fast rides with some forum members through the back country.

I was going to copy the info but I will tag @half_crazy and let him, it's kind of his baby. So if you want to pop wheelies, this is the event to go to. I would definitely go if I could.
 

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Discussion Starter #5
I hear you, but cams are way out of my budget yet, maybe in the future... Do I have to add a PCV if I install the timing wheel ? Or can I do without the PCV for the moment ?

I will check the Spring Horsepower, thanks for the tip.
 

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the timing wheel isn't going to adjust your air/fuel mixture and get rid of the backfiring. You can get a stage 1 flash from a dealer, you can get a Victory Fuel Controller (VFC), PCV, etc.

I don't want to answer on the timing wheel question, as I have avoided installing it. Not because I don't approve, they are great. I just haven't had the need and now with the other options of tuning available, if you plan to add cams then the timing wheel is a waste IMO.
 

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Put the timing wheel in now. It will not cause and problems and you'll not need any tuner

 

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I recently debaffled my Freedom Performance pipes by removing the rear sections with the spiral louvres and getting some plain 2" exhaust pipe bent to suit.
Open pipes sound obnoxious so all I did to mellow it a bit is weld a washer to a bolt and drill a hole to fit it inside the pipes 4" from the end.
The difference is phenomenonal!!
Has to be heard to be believed.!!
Picked up a bit over 5 hp on back to back dyno runs!
Here's some pix.
Simple washer on a bolt commonly called a lollipop baffle....it works!
 

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I've been thinking about having a baffle made or modifying one to fit my bike. I'm upgrading the stereo and the debaffled is getting to be a bit much for me on the long rides or anywhere there is a wall/mountain next to me.

The XC exhaust still has some mesh inside when you remove the baffles, it's not just a pipe but the lollipop idea might work to tone it down a bit. It would be cool to have the ability to twist them open/closed for when you do want it loud as a screaming banshee. I love screaming through tunnels with the loud exhaust lol. Must be my inner child.


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In reading this thread, and some of the responses, it brought a question to mind.

If you alter your exhaust, you will need some means to alter the tune on the bike at the same time.
IE, if you "It would be cool to have the ability to twist them open/closed for when you do want it loud as a screaming banshee." you should be able to switch to a different fuel map at the touch of a button or flash your ecm with a tuner or something like that in order to account for the change. A restricted exhaust most of the time needs not as much fuel as an open or unrestricted exhaust.

Food for thought.:wink
 

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I've been thinking about having a baffle made or modifying one to fit my bike. I'm upgrading the stereo and the debaffled is getting to be a bit much for me on the long rides or anywhere there is a wall/mountain next to me.

The XC exhaust still has some mesh inside when you remove the baffles, it's not just a pipe but the lollipop idea might work to tone it down a bit. It would be cool to have the ability to twist them open/closed for when you do want it loud as a screaming banshee. I love screaming through tunnels with the loud exhaust lol. Must be my inner child.


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Yeah when I read the opening statement of your post I thought you're getting old...
Try the washers they cost nothing but a bit of time if you have a welder and a drill.
A long enough bolt with two nuts would allow you to lock one nut against the other the hold the washer flat against the flow.
Sound travels faster than exhaust gas, soothe washer reflects the sound wave back.
It's still fairly loud but not totally obnoxious.
In my way if thinking anyway.
Experiment away......keep us in the loop
 

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In reading this thread, and some of the responses, it brought a question to mind.



If you alter your exhaust, you will need some means to alter the tune on the bike at the same time.

IE, if you "It would be cool to have the ability to twist them open/closed for when you do want it loud as a screaming banshee." you should be able to switch to a different fuel map at the touch of a button or flash your ecm with a tuner or something like that in order to account for the change. A restricted exhaust most of the time needs not as much fuel as an open or unrestricted exhaust.



Food for thought.:wink


I wouldn't think that adding a little washer to the exhaust would require the setup to change much at all if at all. I currently run the VFC III so if it did I could manually adjust it if needed and just write down the settings between the open and closed washers. It only takes 2 seconds to pop off the side cover and adjust it.


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Yeah when I read the opening statement of your post I thought you're getting old...

Try the washers they cost nothing but a bit of time if you have a welder and a drill.

A long enough bolt with two nuts would allow you to lock one nut against the other the hold the washer flat against the flow.

Sound travels faster than exhaust gas, soothe washer reflects the sound wave back.

It's still fairly loud but not totally obnoxious.

In my way if thinking anyway.

Experiment away......keep us in the loop


It's worth a try. Wouldn't take much effort. I'll try it out when I get home in June. I have a bunch of new parts to install anyway.


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Lollipop washers don't add back pressure,they change the frequency. Sonic pulses play a large role in exhaust tuning.

Some use cones, but lollipops in an open exhaust can help the tuning a bit, just has nothing to do with back pressure.
Exactamundo......
 

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Discussion Starter #17
ok, so what I understand is the washer on a bolt is not going to help with the back pressure, only to tone down the exhaust tone. Correct?
And that If I want to do the timing wheel, I don't need the fuel tuner. But that is another thread...
Thanks again for sharing your thoughts.
Ride safe.
 

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Discussion Starter #18
After my last post the check engine light came on a few days ago without a code. So I took the bike to the dealer for check. Of course the light turn off 5 minutes before I pulled in. they plugged it in and came back with the diagnostic. they said that it shows that I have a stage 1 kit, when all I have is a debaffled exhaust. So the computer needs a re-flash card. At this point I think I will look into a fuel tuner and air filter upgrade. Also have the TPS to install. What you guys recommend?
Thanks.
 

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forget about PCV and go to Maximum it can do more and it will give you trouble codes with a better performance.
Next take a ride up to Kevinx he is one of the top tuners in the country. With exhaust air filter and the Maximum you should be around 95 plus horse power. Kevinx will not steer you wrong.

https://www.facebook.com/kevinxsouthernmotorworx/
 

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ok, so what I understand is the washer on a bolt is not going to help with the back pressure, only to tone down the exhaust tone. Correct?
And that If I want to do the timing wheel, I don't need the fuel tuner. But that is another thread...
.
It's not that simple. Nothing ever is.
The washers do provide back pressure. Pressure by definition is resistance to flow.

These are hot air engines. You generate torque by heating air by adding a fuel to it, then lighting it on fire which increases in volume dramatically in the enclosed area which is the combustion chamber and forces the pistons down the bores, etc. That air is still in a high state of expansion when it heads down the exhaust pipe and their is a lot of it at high RPM.

Picture the engine exhaust gasses hitting the washer. They do cause a restriction to the exhaust gases or resistance which is seen as a measurable rise in pressure. This increases with RPM. They do create back pressure to some extent. Not so much as a tube type baffle would, but even a sharp edged orfice is a restriction. However it is extremely unlikely that installing them will solve all your issues with fuel tuning created by changes made in the exhaust system.

Without getting deep into engine theory your stock cam in your motor has been optimized for the back pressure that exists in your stock exhaust system but because of the design of the valves and ports , the closing point of the exhaust cam, it's low speed operation, this motor isn't as sensitive to changes in back pressure as a smaller more efficient highly tuned motor could be. These are torque monsters. As engines go they don't rev very high hence the six speed , need very little overlap and use early closing cams in stock form. Minor changes in back pressure really don't have drastic affect overall. But that doesn't mean that when you debaffle the exhaust it does not change the pressure in the exhaust pipe or that when you add washers you do not raise the pressure over what it would be on an open pipe.


Removing some of the back pressure will affect the fuel needs of the motor in certain rpm ranges. It's a given.


When you remove some of the back pressure you probably over scavenge the cylinders. This means that some of the gas rich mixture that should have stayed in the combustion chamber flows out into the exhaust valve during the overlap of the cam into the exhaust pipe because the gasses are moving at a higher speed but the exhaust and intake valves stayed open the same number of degrees of crank rotation. Some combustible mixture that got away is no longer burning in the cylinder and expanding against the piston tops to create force at the crank. You loose some torque, some mileage, but with a long stroke motor like these it is hard to detect off the dyno.

If you had performance cams they would be optimized expecting less back pressure and would be less likely to over scavenge.

The fuel map in your bike was originally created for the needs of the motor as it was produced. These motors are run lean to meet EPA emission standards. Lean also means higher internal temperatures. Leaner is even hotter.

Changing the back pressure and flow characteristics of the pipe by removing all or a portion of the baffle will require more fuel to be added in some places in the RPM range more than other areas. Fuel may have to be lessened in other areas because of things such as changes in reversion patterns etc. Just as some team of engineers spent time getting the fuel just right for the engine with the original exhaust someone should now get it right for what it has now become with it's new mods.
 
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