Do the headers from a 4cyl automobile share the same concept as sportbike headers? I remember when looking for an exhaust for my GSXR I saw some different designs that each manufacturer had. I know Micron has their Serpent system which looks like a the primaries are squashed on the first initial bend. Then they got into "hydroforming"(sp?) to create a smooth flow. Yoshimura had tubes in between the primaries joining certain cylinders, but the new design don't have that. Akrapovic headers pretty much looked like long tri-y headers like Hytech.

I mean, yeah they are motorcycles, but yes they are inline 4cyl motors that like to rev to 15000rpm. Why no bends like the kiddracing copy of RMF narrow and Bisimoto? Doesn't seem like there is much 4-1 design in the motorcycle industry.

 

Same theory.

Most I-4 sportbikes have a 1-2-4-3 fire order, so cylinder pairing will be different compared to a Honda 1-3-4-2 fire order.

 

Why is it you hardly see any 4-1 or "knot" like headers for motorcycles? Is it because of limited engine space?

 

Those "knots" are only there to get a certain length primary in a limited amount of space. Lower RPM motors tend to benefit from longer primaries which is where the length is required. Motorcycles operate at much higher RPM's and tend to benefit from shorter primaries which for the most part, fit well in the available space without the need to "knot".