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Old 05-22-2010, 10:03 AM   #21
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I guess I don't understand how a muffler can increase flow over having no pipe, that sounds like breathing with a tuned pipe would be easier than breathing through no pipe at all. As a disclaimer, I am not interested in running an open header, just trying to figure out why people say running open headers makes less power.
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Old 05-22-2010, 10:05 AM   #22
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Old 05-22-2010, 10:06 AM   #23
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Old 05-22-2010, 10:18 AM   #24
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From what I understand those torque cones just increase back pressure. How is that going to positively affect a 4 stroke motor assuming proper tuning is accomplished with and with out the torque cone?
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Old 05-22-2010, 01:05 PM   #25
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I don't know why anyone started talking about no headers on this dude's bike...he never said that.
Yes he did...

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Hey I have a suzuki bandit that the exhaust is off will it hurt to leave it off?
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Old 05-22-2010, 01:18 PM   #26
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I guess I don't understand how a muffler can increase flow over having no pipe, that sounds like breathing with a tuned pipe would be easier than breathing through no pipe at all. As a disclaimer, I am not interested in running an open header, just trying to figure out why people say running open headers makes less power.
A muffler will not increase airflow over having no pipe. No pipe can bend valves so the best option is a straight pipe tuned for the specific application but, a straight pipe can be tuned best for only a certain RPM range.
A modern bike has been tuned to operate best, over a wide range of RPM, with the muffler included. Any change to the exhaust (or intake) will change how the motor runs.
If you have a dyno, hundreds of hours for tuning and some people that know their , you can get better performance, under certain conditions than stock. That's what the aftermarket pipe mfr's do.
A professionally made aftermarket pipe and muffler can give you some performance gains but, like everything else, there are compromises. If you put a full system on a sportbike you can gain horsepower and torque but usually only at the upper RPM range. Usually you will lose a little something down lower.
On a racebike it is worth the lower RPM losses because they aren't riding around at part throttle. On the street, for the money a slip-on is the best option because, although the performance gain will be less, the compromises, the cost and the noise arent as big either.
Since NO bikes have been designed to run with open pipes there are NO gains to be had from running that way. You lose horsepower, torque and likely will be stopped for loud pipes. Mufflers are almost always included in the equation because nobody wants to be around an open exhuast for very long.
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Old 05-22-2010, 03:06 PM   #27
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uh no back pressure. whatever that is
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Old 05-22-2010, 03:12 PM   #28
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Why couldn't you re-tune the carbs or fuel maps to match the less restrictive flow of the open header though? Slip-ons may have been designed to flow better using the bikes factory tuning, but if you can adjust the tuning what is the hold up?
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Old 05-23-2010, 12:03 AM   #29
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Why couldn't you re-tune the carbs or fuel maps to match the less restrictive flow of the open header though? Slip-ons may have been designed to flow better using the bikes factory tuning, but if you can adjust the tuning what is the hold up?
You can adjust for the less restrictive airflow but changing the exhaust and retuning affects the characteristics of the engine.
My previous post describes what usually happens.
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Old 05-23-2010, 12:26 AM   #30
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only time you want little to no backpressure is if you plan on going F/I and getting it tuned.
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Old 05-23-2010, 01:09 AM   #31
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Dont do it, bro!

Officer Coleslaw is gonna get ya!
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Old 05-23-2010, 01:14 AM   #32
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Dont do it, bro!

Officer Coleslaw is gonna get ya!
never understood is the true name coleslaw or coldslaw? Intentionally didn't google it for a MH answer. (yes I mean the delicious side dish)
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Old 05-23-2010, 01:25 AM   #33
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never understood is the true name coleslaw or coldslaw? Intentionally didn't google it for a MH answer. (yes I mean the delicious side dish)
It's coleslaw. Slaw is a style of salad and some named Cole invented this particular one.
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Old 05-23-2010, 01:32 AM   #34
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It's coleslaw. Slaw is a style of salad and some named Cole invented this particular one.
I'd shake his hand for inventing an awesome side dish salad.

edit: we went from moto exhaust to coleslaw... name another thread that went that far off topic. That might even go beyond the 6 degrees of Kevin Bacon.
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Old 05-23-2010, 04:31 AM   #35
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Old 05-23-2010, 08:30 AM   #36
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hit it on the head. Bumblebee rox!


Valve overlap occurs when the intake and exhaust valves are open at the same time, directly after the exhaust stroke and beginning of the intake stroke. Guess what happens when their is no backpressure and your fresh new air/fuel mixture is allowed to fill the cylinder and exit right away?

you lose engine efficiency... no more bang. That small amount of backpressure helps hold back the new mixture. As mentioned before, any engine is like an air pump. On a well designed manifold the exhaust can also have a slight vacuum from the other cylinders pulling the used mixture out of the cylinder.

If it would have made THAT much of a difference and be within tolerances of noise/overall performance and engine wear the factory would have done it.

Remember the race engines are not designed to last long and are pushed hard. The loud cracking noise you hear when running open headers on decel is either a lean condition in the system causing post ignition in the exhaust or air funneling up the exhaust while the exhaust is coming out and post igniting.
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Old 05-23-2010, 09:05 AM   #37
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I'm stunned that you people are treating this like a real question.
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Old 05-23-2010, 12:40 PM   #38
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cat question

well i ended up knowing that my bike is a cali model

for the same reason. it has the cat and all that other to make babies breath better

so the cat must be on for legal matter even in texas?

does take hp if is on?
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nevermind ima bumbass and ill get my wife 2 do it 2nite.
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Old 05-23-2010, 12:45 PM   #39
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Did someone say Bacon?
now from pipes to coleslaw now bacon hashahaha
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Old 05-23-2010, 01:13 PM   #40
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well i ended up knowing that my bike is a cali model

for the same reason. it has the cat and all that other to make babies breath better

so the cat must be on for legal matter even in texas?

does take hp if is on?
You don't need the cat. Take it off and the engine will breathe better and will add HP.
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