440ex jetting problems?

[bjg696]

I got a 440ex with hot cams stage 2, bigger valves, full exhaust, and a port and polish. It keeps cutting out on top end. the exhaust is running a lil white. That means its lean. I have took the carb apart and adjusted it dozens of times and it still wont run right. Anyone have any advice?

[drew416ex]

what size main jet are you running?

[bjg696]

I am running a 185 main right now with the clip on the needle in the middle slot.

[drew416ex]

Hmm... Have you tried going up to a 190 or even down to a 180 to see if it gets better or worse? Just an Idea.

[bjg696]

I went down to a 180 and it got worse. but i have read alot from other people and ther jetting problems, and the most i have seen is a 170. i have also heard goin to a 42 pilot. I am goin to remove the choke in the process. just trying to figure out what i need to do.

[rideracelivemx7]

12:5:1? what octaine are you running?

[rideracelivemx7]

also what is your pilot size?

[bjg696]

Yea its 12.5:1 and i am running strait 110 octain. Im not sure bout the pilot size. It may be stock. I put a dynojet jetting kit in it so whatever may come in that kit.

[xtullyx16]

Originally posted by bjg696
Yea its 12.5:1 and i am running strait 110 octain. Im not sure bout the pilot size. It may be stock. I put a dynojet jetting kit in it so whatever may come in that kit.

is ur main jet part of the dynojet jetting kit?? cause maybe the 180 isnt a real 180 main .. i'd go to ur dealer and get a main jet from them...

[bjg696]

Yea the main i got isnt a dyno jet, its another kind. Ive tried everything possible and nothing changes..

[REPOMAN]

on my 440 i had full sparks exhaust, aluminum air box, ported head, stage 2 hotcam, k&n filter, i was running a 170 main. i also had an aftermarket cdi and coil. i always check whether i am rich or lean on my exhaust also but have you looked at the plug? how is your airbox setup? did this just start happening all of the sudden or has it always done it?

[Def-e-nition]

Originally posted by bjg696
Yea the main i got isnt a dyno jet, its another kind. Ive tried everything possible and nothing changes..

I Think there's your prob.

The dyno Kits are basically up to a 170. thats 1.7 mm .

Some guys run a 170 with airbox off , etc , but in your case running 12:1 , 110 Octane , , Find your 170 Dyno Jet , and just see whether the 180" you have in there is actually bigger than the dyno 170 .I Know it sounds silly , but with a Hc 2 and all those other mods , your bike has all the mods I'd want on mine , so it should be flying .you say you Know it's running Lean , I would simply avoid any confusin and find out what size jet you are running , you seem to know that here is where your problem lies .

[GPracer2500]

Originally posted by bjg696
...It keeps cutting out on top end. the exhaust is running a lil white. That means its lean. I have took the carb apart and adjusted it dozens of times and it still wont run right...

Since your description of what it's doing is kinda vague, I'm just gonna guess about what's happening.


Are you sure you're not hitting the rev limiter? Might be a dumb question, but....

You said "cutting out at the top end". That pretty much describes what happens when the limiter cuts in [shrug]. Also, what throttle position does the cut out occur at? The carb circuits correspond to throttle position, not rpm. A studder that can be attributed to jetting can usually be reproduced at various rpm since it's the throttle position--not the rpm--that corresponds to what the carb is doing (although, a fueling glitch may be more obvious at a specific rpm).

Also, since when is exhaust "running a little white" a sign of lean? That's new to me. I can't think through how being lean would cause white smoke. My guess is the white smoke is a touch of oil finding it's way where it shouldn't be.


Originally posted by bjg696
...Ive tried everything possible and nothing changes...

This is another reason I wonder if your problem is really a jetting problem. If changing the jetting up and down (by a sufficient amount) doesn't directly change the studder, then maybe it's not the jetting at all.

[bjg696]

Ok, well i will go and try to look at the dyno jet 170 compared to my 185 and see hwt the difference is. But it cuts out at half throttle. I will check the plug and see what it looks like. It has been doin it since i did all the work to the head(port and polish and bigger valves). I wouldnt have figured it would have changed it that much. But who knows. This thing has go over 4000 in just the engine so im ready to get it right. Thanks for all the suggestions. I'll let yall know the outcome on it when i try it..............THANKS

[apachepride]

i quess this is were i should have posted this i have the stage 2 dyno jet 170 main stock pilot choke removed, removed air box lid header welds ground aftermarket filter tc 924 cam and sparks degree key im getting ready to put the 440 toghether im in KS 1350 elevation i think compression is 11.1 thanks