Exhaust question

[Ride509]

I see a lot of people putting 4-4 exhaust on bikes. Now I am very function over form . And being a car guy and building some motors I normally try to use a equal length header with a 4-2-1 . The reason is exhaust scavenging . I don't know if this happens on bikes or there just isn't enough exhaust pressure for it to matter but I would think at 6-9k rpm that it would make a big difference in power.


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[Sonreir]

Four into one would be best, but a four in two into one is also good. You can see this in effect on the aftermarket exhausts.

 

[TomTerrific]

Each cylinder will have a slightly unique sound. Individual pipes/mufflers sound nice harmonizing together. You don't get that same quality with a 4 into 1.

Tom

 

[Sonreir]

There are a lot of other reasons than "sound" to choose one exhaust system over another.

 

[TomTerrific]

Of course you are correct, there is engine performance which you've mentioned. Also weight, simplicity of construction, looks... Sound is important to many.

Tom

 

[cklamer]

My engine builder says the 4-2-1 is the way to go for a race engine.
You will lose some in the mid-range with a standard 4 into 1.
Nothing wrong with the 4 in to 1 I had one.
But the race exhaust gives better tuning capabilities.