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2019 CB1000R
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Discussion Starter #1
So, CBRs have a solenoid operated exhaust flapper. Many folks disconnect the flapper cable so that the exhaust flapper is always open.

Today while I was waiting for the engine to warm up on the NSC I noticed that no exhaust was flowing out of the smaller outlet. There must be some type of valve or flapper in the muffler to allow exhaust to flow at higher RPMs. I've checked Honda parts diagrams and detailed installation instructions from Akrapovič and there is no solenoid or flapper cable.

Does anyone know how the muffler on the NCS operates? Is there a valve or flapper in the muffler that is spring loaded and opens when exhaust pressure reaches a certain level?
 

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My former 2K8Z1K had push and pull cables to a valve in the right side mufflers; but, my OEM CB1K muffler had no cable. Maybe the smaller outlet is for looks.
 

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Discussion Starter #4
Maybe the smaller outlet is for looks.
I just stuck my finger in the small outlet and the inside is coated with soot just like the large one. I took the cover off and condensation left a dirty trail under the muffler directly from the small outlet.
 

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Discussion Starter #9
I think the CB hasn't got any valve o flapper.
I wonder what the component (circled in the diagram) at the bottom of the small outlet is? It could open and close.
 

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No flap or valve inside those are 3 holes

From the Honda press folder:

The exhaust pipe can directly exhaust at high speed
The exhaust pipe adopts a single-side single-out dual exhaust port design, which can take into account the extensibility and turning angle at high speeds. At the same time, in order to reduce the weight, the exhaust pipe adopts a simple double-chamber structure, and the exhaust There are 3 small holes in the exhaust port below the inside of the pipe. In addition to expressing the heavy low exhaust sound waves at standby speed, it can also exhaust without going through the second air chamber at medium and high speeds, showing a parallel 4 cylinders. The engine's sense of speed increase.

005-1.jpg
 

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Is the cat the pink colored area in the muffler? I had suspected the cat was in the exhaust box below the motor.
 

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Ok. I see. The cat is in the two header pipes going into the muffler box--typical. Didn't understand the color coding in the graphics.
 

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Discussion Starter #15
Ok. I see. The cat is in the two header pipes going into the muffler box--typical. Didn't understand the color coding in the graphics.
I just think they were trying to illustrate that the muffler has two chambers
 
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