Will the inrease in carburetor size affect the performance much? (35.5mm to 38mm)

 

I think that it's only recommended with other mods but i'm not sure. I just took the choke out of mine today and if helps throttle response.

 

The change from 35.5mm to 38mm is a factory change for the 2004 400EX model. Will the change help the performance much?

 

I should help but i don't know by how much. Did you read this on the honda site?

 

If you go under Hondamotorcycles.com, quads, sport quads, and then 400EX. It has the spec.'s for the 2003 and 2004 models under each year. The carb size is the only noticeable change.

 

wonder if they had to increased the carb size because they changed the cam, piston, and valves for more power???

that would be sweet! at least so it won't be beat by the Z's anymore... that's all they'd have to do

 

It is about time they started doing yearly upgrades on quads!! Look at the MX dirt bikes, they get tons of upgrades every year. The manufacturers just have not given us the respect that we deserve. And, Honda needs to stop being so timid about power if they are going to compete in the marketplace. Competition is good!!!

 

What carb does the XR400 dirt bike have???????

 

reconranger, The 03' XR400R has a 36mm piston-valve.
The 03'/04' CRF450R has a Keihin 40mm flat-slide.

 

Visually the only thing that appears different from the 2003 400EX to the 2004 is the graphics. (very little change) The motor appears to be the same in the 2003 and 2004 pics.