What jetting should I use on my 440ex??

[85atc350x]

I recently had my stock engine built to a 440 with a web cam, ported & polished head, and a 12.5:1 compression ratio. I am running 110 octane race fuel and my elevation is about 300 ft above sea level. The stock main jet is a 148. I installed a 155 mj and it dies at about 1/2 - 3/4 throttle. Do I still need even more jetting??

[da400hon]

Yes. I have a KandN, hotcam, And full system exhaust and i run a 170 main. And i'm at sea level.

[cals400ex]

stock pipe? air box lid on or off? any other mods?

[03dynasty]

If it isn't running well from 1/2-3/4 you probably need to adjust your needle. What kind of jets do you use?

[85atc350x]

Running with airbox lid on and DG exhaust. I've been purchasing my jets from the local Honda dealer.

[03dynasty]

Since I don't know anything about jetting an ex here's a helpful link http://www.exriders.com/jetting/jetting.shtml if it cuts out you are too rich. do you have an adjustable needle? really I can't tell you how to jet, you will have to learn for yourself (unless you like putting money in you dealer's pocket). If it runs fine everywhere but what you said, check your needle.

[Chef]

Keep jetting it up, on the pilot and hte main. Put in a 48 or 50 pilot and up the main to about 170-175. See how it runs then.

[EPDP99]

i think a 48 pilot on a stock carb is way too big. im running a 50 on my 41mmFCR. go with a 42 pilot and defintally up your main to a 165-170 area. But id go richer on the needle(drop the clip down).

[Chef]

Originally posted by EPDP99
i think a 48 pilot on a stock carb is way too big. im running a 50 on my 41mmFCR. go with a 42 pilot and defintally up your main to a 165-170 area. But id go richer on the needle(drop the clip down).

Whoops on the pilot...I am running a 55 and 62 in my 41's so I figured that a 48 would be about right...:chinese: :macho

[EPDP99]

Originally posted by Chef
Whoops on the pilot...I am running a 55 and 62 in my 41's so I figured that a 48 would be about right...:chinese: :macho

your running a 55 and a 62?? im kinda confused bout that.

[Chef]

Originally posted by EPDP99
your running a 55 and a 62?? im kinda confused bout that.

FCR's...2 of em. lol.:scary:

[EPDP99]

haha, see i didnt even know that, mine came "pre-Jetted". all i know is that i got a 50. now that i think about it i did recall seller saying something about a 50 or 52, maybe its got both of those.

[Chef]

Originally posted by EPDP99
haha, see i didnt even know that, mine came "pre-Jetted". all i know is that i got a 50. now that i think about it i did recall seller saying something about a 50 or 52, maybe its got both of those.

Ieant 2 FCR's. 2 separate carbs.

[EPDP99]

phewwww, i was seriously getting confused. i was like there isnt two, but i havent done that much research on them.

[zippy]

go on ebay and do a search for a jet kit that is NOT dyno jet. there are some kits that offer alot of jets for a reasonable price.

[85atc350x]

I just wamted to say thanks for the suggestions on my carb settings. I bumped the main jet to a 175, The pilot to a 48, Dropped down 1 notch on the needle, And removed the airbox lid. My 400ex runs like a raped ape now.:D