[Joker]

If I put a 450r Carb On my 2005 400ex. What improvement am I going to be gaining? Will I have to change anything else when I put it on?

 

[Redracer]

You will be able to take in more air and more gas. Jetting will be required

 

[tomgodd]

Agree^^^^^^^^^^^
The 450r carb is bigger. I have never seen this done, so if you do this make sure you keep us informed.

 

[TTRCR414]

i have a 450R carb but i run an edlebrock its supposed to be a bolt on jet it and be done and a bigger carb gives you better throttle response

 

[TRX2fiveO]

A BIG PITA if you ask me. I put a 400ex carb on my 250X what a nightmare to jet, the air induction is so much larger. im pretty close now though I think when I install the Port and polished head it will be right.