400ex Carb specifics STOCK

[ezdaar]

Im ready to pull alil more power from my 300 and figure the 400 carb is the cheapest and simplest way to go.

I do not need jetting help as I will be tuning with a wideband and will have my jetting spot on.

Mainly need to know what year is the best and why.
Are they all pumper carbs?
Does the throat size vary from year to year?
Does the stock jetting change?

Basicly I'm looking for intimate details which I have not found here via the search engine.

Please No guessing, Need solid facts.
Thanks for your time.

[BEAVER.989]

They appear to be different.

99-04...

http://partsfinder.onlinemicrofiche.com/servicehonda/Honda_OEM/HondaATV.asp?Type=13&A=136&B=22

05-up

http://partsfinder.onlinemicrofiche.com/servicehonda/Honda_OEM/HondaATV.asp?Type=13&A=235&B=8

[GPracer2500]

The 99-04 carb came with an adjustable needle and a normally slotted fuel screw. I might look for one of those for that reason. Beyond that there's really no reason to choose one year over another.


And regarding the 35.5mm vs 38mm comments I'm sure are forthcoming, it's been discussed before....

http://www.exriders.com/vbb/showthread.php?s=&threadid=326000&highlight=literature

[ezdaar]

Kick***** that explains everything I needed to know.
Thanks a ton for the supplied info!

Well heres one last question.. I noticed while looking on fleabay that there are differences in the throttle linkage cover on the side of the carb.
Which one is the early style? As I now know I want the early model carb.

Basicly Im asking how to -Visually- ID a 99-04 carb vs the 05-newer carb... Other than the D shaped mixture screw, Which NOone on fleabay shoots a pic of..


Thanks again guys for the help.

[GPracer2500]

You talking about the one laying in the grass? Something is strange about that particular carb. The cover is different because it appears there's no air cut-off valve on that carb. Weird. Almost everything about it appears to be 400EX except no ACV and some minor casting shape differences.

All 400ex carbs I've seen have identical linkage covers and an ACV. Plus, the part number for that cover has not changed '99-'08.

Maybe it's from a foreign market 400ex or something [shrug]. It's odd. I'd steer clear of it.


The only exterior physical difference I know of is at some point they went from a single left side vent nipple to two nipples. The duel nipples have their hoses joined with a 2-into-1 plastic fitting. I'd guess that change occurred '99-'04 vs 05+ but I'm not 100 % sure.