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homemade powerbomb header

By viking_in_wa,
in YZ400F/426F/450F/450FX

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kizzle426

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That bulge is actually like a tiny pre-muffler. It has a perforated core and I think possibly packing. If you go to the FMF website you can see a cross section of it and if you e-mail them, they might send you a picture of the inside too, just don't them what it's for. Just making sure you know what it's made of ?

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Lizard 1

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That bulge is actually like a tiny pre-muffler. It has a perforated core and I think possibly packing. If you go to the FMF website you can see a cross section of it and if you e-mail them, they might send you a picture of the inside too, just don't them what it's for. Just making sure you know what it's made of ?

No packing and not perforated like an insert on a muffler. Here's a shot of the Mega.

http://www.transworldmotocross.com/mx/gohuge/0,20859,1010783_1156766,00.html

I'd be careful as where it is located is probably as researched as it's design... If you are ready to experiment, go for it, but in reality, it will probably be cheaper to just buy one from FMF once you tally the costs of Titanium and the welding supplies.... Oh, and your time is worth something.

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Raven1911

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I don't think anyone is going to go out and tell on you if you make your own head pipe. If they do and FMF calls you then maybe you will have a sweet job?? ? I say go for it! I believe they need to be a certain length too right, just like car headers?? ? I wish I had a welder to try and tinker like yourself. Post pics when you are done! :bonk:

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vorra65

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Go for it, looks like it wouldn't be all that hard to duplicate. The stock bend has been "ventilated" then they welded the cone's upstream/downstream then added the center piece into place over the ventilated section.If you have the equipment and can Tig-that's half the battle.

Let us know how it goe's-pic's and such. ?

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grayracer513

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No packing and not perforated like an insert on a muffler. Here's a shot of the Mega.

http://www.transworldmotocross.com/mx/gohuge/0,20859,1010783_1156766,00.html

I'd be careful as where it is located is probably as researched as it's design... If you are ready to experiment, go for it, but in reality, it will probably be cheaper to just buy one from FMF once you tally the costs of Titanium and the welding supplies.... Oh, and your time is worth something.

The Power Bomb did not have any packing, either, but the core was more heavily perforated than the Mega. As I recall, there were 7 to 9mm holes arranged in perhaps 8 staggered rows running parallel to the pipe axis, about 4, maybe 5 to a row.
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Lizard 1

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I don't think anyone is going to go out and tell on you if you make your own head pipe. If they do and FMF calls you then maybe you will have a sweet job?? ? I say go for it! I believe they need to be a certain length too right, just like car headers?? ? I wish I had a welder to try and tinker like yourself. Post pics when you are done! :bonk:

When I stated the placement was as researched as the way it was built, I meant that where he puts it can be good or bad, most likely. Kinda like messing with a mid-pipe on a sport bike. We used to dyno different lengths for changing mid-range, etc. So, in theory, if he places it a certain way, he could possibly move his power around a bit.

Just seems wierd that for the cost of the titanium and the cost of the welding supplies - it ain't cheap - he could just go out and buy one to slap on.

Of course, what fun would that be, though...I'd say try it out and see. Hell, if not for the experiment factor, maybe for the bling. It would be pretty damn cool to do one on your own. Pretty trick if he can weld Ti well...

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grayracer513

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If you can't buy the materials for far less than the nearly $300 FMF wants for the pipe, I'd be really surprised. Besides, he could use stainless for far less, and even build one from mild steel and powder coat it.

The position of the 'bomb' and its internal construction are probably quite important, and the result of a considerable amount of research, but you might get some pretty good results from carefully measuring one and copying as close as you can.

The theory of operation is this: The exhaust pulse inside a head pipe produces positive waves in front of it as it enters and travels down the pipe. When the positive wave reaches the end of the pipe or any significant increase in cross section, the expansion of the gases into this larger section causes a negative (low pressure, or vacuum) wave to be "reflected" back toward the open exhaust valve. Headers and exhaust systems are tuned to cause this lower pressure wave to arrive at the valve at the most opportune time, so that it can help remove the last of the exhaust gases, and even assist bringing in the intake charge.

The trouble is that this kind of harmonic resonance synchronizing is effective only within a fairly narrow range, so you have to decide where you can best use the help.

The Power Bomb is designed to work by damping the pressure waves and cause the header to "appear" to the engine as if it were of an undefined length, which is intended to broaden the range of its effectiveness, and the cooling effect of the gases expanding into the 'bomb' lowers the pressure in the pipe to help speed the extraction of the exhaust. The header is effective in accomplishing that to some extent, and usually results in a widening and flattening of the power curve more than an outright gain in peak power. That might not be what a road or drag racer is after, but it's very useful on a dirt bike.

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Raven1911

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When I stated the placement was as researched as the way it was built, I meant that where he puts it can be good or bad, most likely. Kinda like messing with a mid-pipe on a sport bike. We used to dyno different lengths for changing mid-range, etc. So, in theory, if he places it a certain way, he could possibly move his power around a bit.

Just seems wierd that for the cost of the titanium and the cost of the welding supplies - it ain't cheap - he could just go out and buy one to slap on.

Of course, what fun would that be, though...I'd say try it out and see. Hell, if not for the experiment factor, maybe for the bling. It would be pretty damn cool to do one on your own. Pretty trick if he can weld Ti well...

Gotcha! I thought you were talking about some sort of infringement or something. ? Man....if I only had a welder I could have some fun!

When you dyno'd bikes did you notice any consistencies between bikes. ie: longer pipe means stronger midrange, shorter pipe = ??, or does it depend on the individual bike?? This might help him in building his pipe! haha "Building his pipe!" Have fun!!! ?:bonk:

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Lizard 1

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If you can't buy the materials for far less than the nearly $300 FMF wants for the pipe, I'd be really surprised. Besides, he could use stainless for far less, and even build one from mild steel and powder coat it.

The position of the 'bomb' and its internal construction are probably quite important, and the result of a considerable amount of research, but you might get some pretty good results from carefully measuring one and copying as close as you can.

The theory of operation is this: The exhaust pulse inside a head pipe produces positive waves in front of it as it enters and travels down the pipe. When the positive wave reaches the end of the pipe or any significant increase in cross section, the expansion of the gases into this larger section causes a negative (low pressure, or vacuum) wave to be "reflected" back toward the open exhaust valve. Headers and exhaust systems are tuned to cause this lower pressure wave to arrive at the valve at the most opportune time, so that it can help remove the last of the exhaust gases, and even assist bringing in the intake charge.

The trouble is that this kind of harmonic resonance synchronizing is effective only within a fairly narrow range, so you have to decide where you can best use the help.

The Power Bomb is designed to work by damping the pressure waves and cause the header to "appear" to the engine as if it were of an undefined length, which is intended to broaden the range of its effectiveness, and the cooling effect of the gases expanding into the 'bomb' lowers the pressure in the pipe to help speed the extraction of the exhaust. The header is effective in accomplishing that to some extent, and usually results in a widening and flattening of the power curve more than an outright gain in peak power. That might not be what a road or drag racer is after, but it's very useful on a dirt bike.

Man, raw titanium in the grade used by FMF and others is kinda pricey. plus, he'd need flat sheet to develope a cone shape and a bit of larger tubing for the center (outside). plus, the wire is pricey, too.

Another thing is that there are few people who can weld Ti rather well. Most the time when we had Ti canisters needing of repair, we'd go to a local airport. There's always guys there welding Ti. Even patch jobs were close to $100 for a small 2" square piece...

I think doing it in stainless would be cool. Even still, the cost in doing one is going to be high - creating a jig, the material and welding material. Stainless would be far cheaper, but why mess with stainless? Go big and do a Ti pipe. The welding will create a work of art with the blueing and gold and marking you get with custom Ti pipe making... VERY cool...

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kizzle426

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No packing and not perforated like an insert on a muffler. Here's a shot of the Mega.

http://www.transworldmotocross.com/mx/gohuge/0,20859,1010783_1156766,00.html

I'd be careful as where it is located is probably as researched as it's design... If you are ready to experiment, go for it, but in reality, it will probably be cheaper to just buy one from FMF once you tally the costs of Titanium and the welding supplies.... Oh, and your time is worth something.

I was thinking of the regular power bomb. I've seen a cut away and it was rather 'holy', no pun intended. I just wasn't sure if when it wasn't a cut away shot like that, if it had packing or not. Can anyone explain to me how that adds power? I'm dumbfounded.

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aford541

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Has anybody tried to fab up a powerbomb like head pipe yet? I am a welder by trade and i will have an extra head pipe soon to tinker with. Shouldnt be too tough to make one. give some feedback here and let me know if youve tried this yet or what you think.

Man, if I won the lottery Id buy a dyno and a bunch of tools and rent me a commercial building and go to town.

I designed a muffler a while ago that I would like to build and test but there's that whole time and money thing.

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Lizard 1

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be carefull or your plan could make you loose power!!!!!

That's kinda what I am trying to convey, but seemingly, no one seems to understand that even after the cost issue, it is a system that has been researched rather well and it isn't just slap it on and run. To be most effestive, you need ample dyno time, more materials than to make just one, and certainly the willingness to make mistakes.

All that added up and I would vote more along the lines of spending $300 to buy it at retail.

Hell, taking the time to convince a dealership to give you employee cost would be better time spent to save money on the thing...

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viking_in_wa

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Well the thing is that i have access to all of the material free of charge and a full shop set up with lathes and mills and such, i can manufacture anything i want, most parts for our "23" t-bucket roadster and 34 ford have been home made right here in the shop. I just it might be kinda fun to build a head pipe and chew up a little time as i have been off work a few months from serious back injury. Im really bored.

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