Difference between a 4-stroke header with smaller and bigger diameter.

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1/4/2018 1:50 PM


Please shed some light..
In my experience, on my previous kx450f 2017 i put a yoshimura header (which has bigger diameter than stock) with the stock slip on and it felt like it had more low power but made it smoother at the same time and it was kinda perfect. (Plus the sound changed completely... it was similar with the one the bike makes when you have the yoshi slip-on too on.)
So... what would a header with smaller diameter do? make it a bit more aggressive and give better top performance?
I have no experience with thinner header so I just guessed.
ALSO. What would be the difference with an FMF header with a power bomb on? My guess is that it would have similar bottom power with stock one but would enter the middle kind of aggressively and would improve more mid-top power basically. ???
Hoping to find that mechanic guy who just knows... and can explain. I'd really appreciate it if you guys shared some knowledge/experience


1/4/2018 5:43 PM

I know a lot of guys in SX use a longer header to increase bottom end. I'm not real sure about the size/diameter of it.


1/5/2018 5:12 AM

Thanks for replying! Is this true? So what does a shorter header do? Come on people get this post rolling it is interesting.
Figuring out what different sized in diameter or length headers do would be like a guide to improve your bike the way you want without spending a fortune for the whole system.