May 26th, 2016, 02:27 PM | #1 |
Daily Ninjette rider
Name: Hernan
Location: Florida
Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot.
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Why Do My Exhaust Headers Have Crossover Tubes?
Copied from
http://www.cycleworld.com/2015/06/26...rossover-tubes "Lots of motorcycle makers do this. The first time I saw such crossover tubes was on the Yoshimura 750 Superbikes. The torque-boosting effect of exhaust pipes arises as follows: As the exhaust valve(s) of a cylinder open, a positive wave of pressure travels down the pipe. When it comes to any point of expansion (such as when it joins a collectors pipe, or when it reaches atmosphere), that wave of expansion also expands back up the pipe. If it arrives in the cylinder during valve overlap (exhaust not yet quite closed, intakes just beginning to open), it draws out residual exhaust gas in the combustion space and can even propagate into the intake system, causing intake flow to begin even before the piston has moved downward on its intake stroke. Because positive and negative waves alternate in the pipe, at some lower rpm it is a positive wave that arrives at the cylinder during overlap. This reduces torque at this rpm by stuffing more exhaust gas back into the cylinder and into the intake ducts, thereby delaying the intake process. In motorcycles with carburetors, the positive wave also causes an over-rich condition, as the carburetor adds fuel to flowing air no matter which way it moves. By providing another point of expansion, crossover tubes—which are often quite small—can broaden the rpm range over which the negative wave arrives during overlap, thereby improving cylinder filling and power." - Kevin Cameron
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May 26th, 2016, 05:27 PM | #2 |
I'm crazy,your excuse is?
Name: Winston
Location: Connecticut
Join Date: May 2013 Motorcycle(s): 250 2007 ninja Posts: A lot.
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To get to the other side?
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2 out of 2 members found this post helpful. |
May 26th, 2016, 08:54 PM | #3 |
cadd cadd cadd
Name: Cadd
Location: 41°21'13.1"N, 74°41'37.4"W
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Why did the chicken cross the road?
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Riding it like I financed it. |
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May 27th, 2016, 06:51 AM | #4 |
Rev Limiter
Name: Jay
Location: WI
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I'm guessing that in a race situation where you are looking for peak power only, you would not want to have crossovers tubes.
Anyone know for sure? |
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May 27th, 2016, 06:59 AM | #5 |
ᗧ•••ᗣ•ᗣᗣ•••ᗣ
Name: Nick
Location: NY
Join Date: Nov 2013 Motorcycle(s): 2009 Ninja 250R and 2014 Triumph 675R Posts: A lot.
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@cadd @crazymadbastard
I believe it's called mating, a rare event that occurs in nature when one header and another decide to get passionate. How else do you think headers are made? They aren't A sexual.
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Spoiler for topic:
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May 27th, 2016, 08:40 AM | #6 |
Fighting Texas Aggie '05
Name: Neil
Location: Hutto, TX
Join Date: Feb 2009 Motorcycle(s): '07 ZX6R, '08 Versys, '09 250R Track, '93 F2/F3 Track Posts: A lot.
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In general from what I have been exposed to, that is correct.
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May 27th, 2016, 10:45 AM | #7 |
in your machine
Name: Scott
Location: Summer Shade, Ky.
Join Date: Oct 2014 Motorcycle(s): 98 Ninja 250/F12 aka ZX-2R "SERENITY", 91 Ninja 500/A5 aka ZX-5R "Phoenix", 84 Honda GL1200A "SIREN" Posts: A lot.
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I know on cars, I've done the crossover pipe to help make I'd quieter, as far as flow goes it could help to reduce back pressure. Going thru two mufflers is better than one.
I think.....
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May 27th, 2016, 11:18 AM | #8 |
Vintage Screwball
Name: B
Location: Washington
Join Date: Feb 2016 Motorcycle(s): 2011 Ninja 250, 2008 Ninja 250, 2019 KTM 1290SDR, 2017 FZ10 Posts: A lot.
MOTM - Mar '16
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Short answer: Torque.
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June 21st, 2016, 07:09 AM | #9 |
ninjette.org dude
Name: 1 guess :-)
Location: SF Bay Area
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Also the answer to "what was one of the worst motorcycling movies made"
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