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The Philosopher King
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1,345 Posts
Discussion Starter · #1 ·
Okay has some of you may or may not remember I recently discovered a rather large hole in the base of my end can where the pipe meets the can. I pulled the can off today so I could have a look at the damages and see how best to fix it…but I couldn’t resist…so while the end can was off I went for a rip up Seymour…and fuck me was it loud my ears are still ringing. Anyways this is what I discovered (I am sure some of you already knew).

-My power band was shrunk by almost 1500rpm. This means it was effectively moved from a 3800rpm power band range to a 1700rpm power band range. It started at 4800rpm with the end can and ended about 7000rpm. Without the end can it started at 5500 and ended at about 7000.

-My power band was considerably more powerful…considerably

-I was hitting higher speeds in lower gears with the end can off

-it was really fucking loud…good thing I wasn’t down town

-I could still take off from a stop at 1200rpm (and I am a big guy)

-I had a lot of back firing when down shifting for corners at higher speeds. At low speeds it wasn’t noticeable.

Now my questions for the tech guys

1) Does the length of the end can make a difference? ie) if I were to cut my exhaust can in half but properly re-sealed it, re-welded it so it was the same thing just shorter what would happen?
2) Can you actually do any damage from running the motor without the exhaust can?
3) Any other comments etc always appreciated.
 

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The Philosopher King
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1,345 Posts
Discussion Starter · #2 ·

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My Twitter: SH1FTG34R
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1,891 Posts
Hmmm I have no comment because I am a noob at this kind of stuff but I can't wait to read some of the replies, especially from TeeTee :p
 

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365 Posts
What you've discovered for yourself is that it's a Tuned System. Yup direct from the factory. Always amusing to see/hear of people buying stupid priced Mufflers in the belief that they can get more power. Yeah that's likely wiuth the Resources of major moto Mfg's at play and industry reputations at stake. More noise at best, and possibly a slightly rearranged power band. Do you think for a moment that the Engineers who designed the Moto had no clue what they were up to when they designed the thing??
Seemingly lotsa fools do :).
Short answer: don't F with it.. it works Fine OEM.
 

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Premium Member
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11,196 Posts
If you've got the ability to weld it up then shortening it by a couple of inches won't make a noticable difference.

Technically you're loosing some volume so your top end should suffer a little but most likely you'd need a dyno to feel the difference.
 

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The Philosopher King
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1,345 Posts
Discussion Starter · #6 ·
Now Bruce why does the loss in volume equal the loss in top speed?? That is where I am stuck, I can't figure out the mechanics of it. Is it the lose of backpressure due to less volume that effects the top speed or what??
 

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Eh Muh Gawd Becky!!
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6,648 Posts
it all has to do with exhaust gas velocity. as was pointed out, its a tuned pipe meaning that someone tested and found the best length for you pipe to give it maximum scavenging. shortening or lengthening will move your power band around as you've discovered but that's basically it. well ok there's a whole lot more dealing with exhaust pulses and such but i don't really need to get into it.
 
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