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Discussion Starter · #1 ·
I have a motoworks SR-4 and according to Motoworks this can't be made into a full system. So, I searched and found an old post where somebody mentioned you could use an FMF header for a motoworks SR-4 exhaust. I couldn't find anywhere saying this would work for sure or anybody that has done this. So I'm wanting to know if this is possible?

Daniel
 

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Im also wondering about doing this mod because HMF slip on has to be sent back,id rather buy a powerbomb header and have it welded then send it back
 

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If the Motorworks fits the stock header, the powerbomb will get you little if any power because the Motorworks would now be your greatest exhaust restriction.
 

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Discussion Starter · #4 ·
So my motoworks will fit the powerbomb header? but you don't think it will give me much more power than just the slip on? I'm not completely understanding this because with the powerbomb and my slip on would be kinda like a full system wouldn't it? or am i mis understanding everything
 

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Slip on exhausts are made to attach to a stock header and a stock header is a smaller diameter than the header on a full system. It's in this larger diameter header that you get the most gains. A full system carries this larger diameter from the header through the exhaust. So connecting your Motoworks slip on to another after market header of the same diameter will not get you much improvement.

roadkill
 

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Discussion Starter · #6 ·
If the fmf slip on fits the powerbomb and I don't know that it does I just read on here that it does then what good does is powerbomb with any exhaust? I'm not trying to sound like an idiot I'm just trying to learn a little bit and I appreciate the replies.
 

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Ok I will try again. When talking about exhaust, larger diameter = good. smaller diameter = bad. The smallest point in any system is the limit of how much the exhaust will flow. More flow=good, less flow=bad.

That being said the stock headpipe and muffler is smaller in diameter than the FMF pipe. The Motorworks pipe has a small diameter pipe where it attaches to the stock headpipe. Overall the Motoworks is going to flow better than the stock muffler. Now if you install the FMF powerbomb headpipe with an adapter of some sort to the Motoworks muffler, the Motoworks muffler now becomes the exhaust's greatest restriction due to the small inlet the muffler. FMF sells their larger diameter inlet mufflers with a reducer to fit the stock pipe so if in the future you want to up grade to a full exhaust you don't have to buy another muffler just install the new Powerbomb headpipe and get rid of the restrictive adapter.

This thread may help> http://www.club700xx.com/vb/showthread.php?t=2305&highlight=fmf*
 

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Discussion Starter · #8 ·
Thank you. you just made it all make sense. I didn't know that the FMF slip on came with an adaptor to make it work with the stock head pipe. thats all that was needed to be said cuz now it all makes sense.
You can buy FMF slip on and use adaptor to make it work with stock header and when you buy the powerbomb you remove the adaptor to make it work with the powerbomb correct? that makes sense now
 

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Thank you. you just made it all make sense. I didn't know that the FMF slip on came with an adaptor to make it work with the stock head pipe. thats all that was needed to be said cuz now it all makes sense.
You can buy FMF slip on and use adaptor to make it work with stock header and when you buy the powerbomb you remove the adaptor to make it work with the powerbomb correct? that makes sense now

You got it. :tup:
 

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While on the subject of the fmf powerbomb header, does anyone know what the expansion chamber does & how it works ? Is it superior to a good quality conventional aftermarket header pipe , or is it just a gimmick thing to differentiate thier product from all the others ?
 

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While on the subject of the fmf powerbomb header, does anyone know what the expansion chamber does & how it works ? Is it superior to a good quality conventional aftermarket header pipe , or is it just a gimmick thing to differentiate thier product from all the others ?
It is a quality exhaust, but I think the Powerbomb is just marketing IMHO. A comparison test would be interesting.
 

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Does anyone know how the FMF full system with a FMF fuel controller compares to the big three thru EHS with a barker exhaust? It looks like they are comparable in cost.
 

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While on the subject of the fmf powerbomb header, does anyone know what the expansion chamber does & how it works ? Is it superior to a good quality conventional aftermarket header pipe , or is it just a gimmick thing to differentiate thier product from all the others ?
The thought is to create a ventura effect by opening into the larger chamber. It's possible to be of benefit, to what degree would prolly be marginal.
 

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The thought is to create a ventura effect by opening into the larger chamber. It's possible to be of benefit, to what degree would prolly be marginal.
Would that be Ace Ventura?
 

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Hydraulic venturi I presume. I dont know that it is the intended design principal. I would be interested to know FMF's thought process though. Nobody else that I am aware of has done that. Maybe its patented though. Its such a small expansion chamber that I would really be interested to know how its supposed to help.
 

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The venturi effect should speed up the exhaust gasses as they approach the chamber, but on exit they will bottleneck again, I just can't get my head around how this would help overall with increased/faster exhaust flow. Interestingly FMF also claim a small Db reduction with the pipe fitted as well.
 

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The venturi effect should speed up the exhaust gasses as they approach the chamber, but on exit they will bottleneck again, I just can't get my head around how this would help overall with increased/faster exhaust flow. Interestingly FMF also claim a small Db reduction with the pipe fitted as well.
There is no venturi, nor is there any claim of a ventri in this pipe.
I seriously doubt it has much if any power over a standard pipe. I think it may even make less power than a standard pipe, but this is just my opinion. It would take a side by side dyno comparison to know for sure. Chamber type of technology is normally associated with a 2 stroke.

From FMF website:

The redesigned PowerBomb is a four-stroke header that incorporates FMF’s patented PowerBomb module at a precise location in the initial stage of the header. By positioning this “Bomb” at a key point in the system, increased performance and flow is achieved through the expansion and contraction of exhaust sonics through the system. Result is a flow increase of nearly 10%! The outer chamber in the Powerbomb allows the air to expand, cool and ramp back up at a higher velocity.
Additionally, the PowerBomb is a “pre-muffler” of sorts which helps to lower the bikes sound output by providing more sound absorbing surface area for the sound medium (exhaust gases). On some models, you can choose between a moto or supercross version. The supercross version is designed for more low to mid-range power where the moto version is focused in the mid to upper RPM range.
 

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There is no venturi, nor is there any claim of a ventri in this pipe.
I seriously doubt it has much if any power over a standard pipe. I think it may even make less power than a standard pipe, but this is just my opinion. It would take a side by side dyno comparison to know for sure. Chamber type of technology is normally associated with a 2 stroke.

From FMF website:

The redesigned PowerBomb is a four-stroke header that incorporates FMF’s patented PowerBomb module at a precise location in the initial stage of the header. By positioning this “Bomb” at a key point in the system, increased performance and flow is achieved through the expansion and contraction of exhaust sonics through the system. Result is a flow increase of nearly 10%! The outer chamber in the Powerbomb allows the air to expand, cool and ramp back up at a higher velocity.
Additionally, the PowerBomb is a “pre-muffler” of sorts which helps to lower the bikes sound output by providing more sound absorbing surface area for the sound medium (exhaust gases). On some models, you can choose between a moto or supercross version. The supercross version is designed for more low to mid-range power where the moto version is focused in the mid to upper RPM range.
The FMF description is describing a venturi effect, Low and mid range would see gains but I'm not sure the effect on top end. If the muffler isn't restricting flow on the top end and minimal back pressure is present it may not have any ill effects up top.
 
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