400ex, new alien setup, jet problems!

[White97GTVert]

Hi there. New poster to the forums! This is long.. Sorry!

Okay, so I have a stock 2000 400ex. I added a K&N Filter, the outerwear, and then the assorted other Dynojet goodies that came with the K&N kit... Yeah, I know.. some people don't seem to have good luck with these.

While still stock exhaust I installed the k&n, outerwear, and the dynojet adapter, needle (3rd position from top) and set the fuel screw to 2 1/2 turns out. Stock pilot jet. I put the main jet as a 160 because the next day I planned on installing my DMC Alien exhaust. It ran pretty good (a little rich, but to be expected with 160 mj)

Installed Alien the following day. Runs at idle no problem off idle a little hesitation and then cuts off and dies mid throttle unless you slowly thumb into it... Not a whole lot of popping @ wot but this was not under load.

Today I dug into the problem of the mid-range cut outs... Did the plug check thing where I warmed it up, rode it around, and then half throttled it till it died, then hit the kill switch, and then pulled the plug. Looked lean to me. (Whitish) .. I pulled the carb apart and moved the needle clip down (richer) by 1. Put all back together and now it won't start. Plug doesn't look fouled.

Does anybody else have experience with the DMC exhausts... I did a search and found a guy who recommended a 40 pilot, 165 MJ, 2 1/2 turns on the fuel screw and said his ran good.. Didn't say whether the 165 was a Dynojet or Keihin. Confused!

When I stab the throttle to mid or full and it just cuts out like you hit the kill switch is that incredibly rich or incredibly lean?

Thanks for reading this lengthy post!

Chad
2000 400ex

[White97GTVert]

Also, once a plug "fouls" is there any way to bring it back or do you just have to junk it?

[cals400ex]

a 165 dynojet will be too big. i would only run around a 158 keihin or 155 dynojet with your setup. i would try the clip in the 3rd position. a 40 or 42 pilot jet should be fine. the fuel skrew with these pilots should be around 2-3 turns out. also, i would take the carb off and spray the heck out of it with carb cleaner. make sure none of the hoses are clogged on the carb either. make sure you don't have an air leak where the carb is clamped on to the two air boots. good luck

[dariusld]

Are you running with or without your air box lid on? It sounds like your running lean from the description. I had the DMC and K&N jet kit and installed the jetting the directions told me to and it ran great, a little rich but it pulled hard.

[White97GTVert]

I have tried it with the lid on and off.. Think I fouled the plug so buying a new one and continuing tonight. When you tip into mid throttle and it just "shuts off" would that indicate a rich or lean condition... I try to read the plugs but it's really hard to do cuz you have to ride it and get it to cut off and then kill it without it starting to pick up (somtimes it will kill out and then all of sudden start to pull)

I did notice that at the bottom when the slide touches (needle goes into) that that brass thing looks to be partly broken off. I am assuming this is the venturi.. Does anybody else know if it should be a complete circle? If so it may have been screwed up by the previous owner. Can I repair it?

Thanks in advance!

Chad

[speedy400]

I'm not sure about your last question but I know exactly the feeling your getting, only time I have gotten that was once when my dad had forgotton to dry his airfilter(all wet filter,idled fine but when you gave it any gas it would studder and want to kill and barely run. The other time was when i ran out of gas... make sure all your lines are good and clean along with your carb, make sure the fuel inlet(needle and seat) are working properly along with the float. And maybe put some new gas in. I'm not sure but thats what it sounds to me. good luck -darren

Edit, Also I remeber when I had just put in my 416 kit, it had done that, turns out I had the wrong pilot in.

[khen]

If it's lean it makes a different sound than if it is rich. It's hard to describe the differences but if it's lean it sounds like bwaaa and then dies. If it's rich it will sputter before it dies. Silly description I know.. Sounds like it is lean to me though. When you pull the plug after it dies is it wet?

[White97GTVert]

Well the problem just got progressively worse so I decided to take apart and clean the carb just in case. So, I pulled everything apart (slide, dynojet needle, dynojet main jet adapter, etc)

Sprayed carb clean thru all the wholes, the slide, the barrell of the carb.. Everything... Let it dry out really good.

Okay, so per other threads I have read the pilot jet should have probably been replaced. I swapped it to a #40 pilot jet. Hopefull that is a little better.

I also ditched the dynojet stuff... Bye bye! Switched back to keihin main jets (tried 160 first, VERY rich, backed out to 152 now)

The fuel screw is 2 turns out right now.. Was 1 1/2, also 1 3/4. Seems to idle just fine, but as soon as I tip into the throttle it starts to sputter and die. It's impossible to ride this way so I don't know how to check the plug properly.

My hope by doing this is that the experts who aren't running the dynojet stuff will be able to chime in. Okay.. so lets have it! :cool:

By the way, if I put the choke on I can full throttle it.. It does not run well but as least it doesn't just up and die. Without the choke on, if I go anything over idle it just dies... Not a lot of sputtering or anything, just shuts off... I don't get it! I checked the manifold boot, no cracks, tightened it to be sure... This is weird and it sucks .. I am supposed to leave to go riding this weekend and I am dead in the water..

[khen]

Sounds like it is sucking air from somewhere. I'm trying to picture the brass part that you say might be broken.. Could it be preventing the gas from being siphoned effectively from the float bowl into the venturi? Perhaps it's siphoning air? Kind of like sucking soda through a cracked straw.

Or maybe somthing in the fuel inlet system is slowing the flow of fuel to the carb float bowl. Maybe the fuel filter(screen) is clogged? I've had this happen before with symptons very similar to the ones you are describing. You can drive around at idle or in some cases just above but when you gas it you starve the float bowl and it dies.

It's really odd that this occured after installing your exhaust. To me it seems the exhaust shouldn't have that dramatic of an effect on your jetting. :confused:

[White97GTVert]

I agree with you... It shouldn't have been that big of a difference. I wll grab the camera and take a picture of the brass piece (part of the needle assembly according to honda service)...

Got the true story on this tonight as well.. Friend who helped me do original Dynojet Install the other night thought it was the main jet (looking from top down into the carb, slide and needle out) and tried to twist it with needle nose.. He thought however that it didn't break anything loose... It doesn't look good to me however.

Honda service says $35 for the needle assembly which is the only way you can get this piece. Do you have any clue which piece I am talking about now? .. For sure the slide, when all the way down, sits on this thing...

I found a used 400ex carb on ebay for around 25 bucks and am trying to just get that instead of ordering all these parts to fix my carburetor.

Do you think the keihin 152 mj is too small for the full exhaust with the filter and the airbox open?

[cals400ex]

what is the temperature and elevation you ride in and i should be able to tune your bike in good. check out this pic. tell me what is broke or what your having problems with:

http://www.servicehonda.com/hard%20parts/atv/trx400ex%2099-04/trx400ex%20frames%20page.htm

[White97GTVert]

I would have to say its #2... It is literally inside the barell of the carb, and the needle goes down into it to get to the main jet .. Looks like its kind half broken off. I have feeling it is causing some fuel atomization problems or something.

Does this make sense now that you know possibly which part I am talking about?

Oh yeah.. I'm in Seattle... Been around 55-60* here and rainy (of course) around 400' elevation.

Thanks so much!

[cals400ex]

with # 2 you get the jet needle (needle), c-clip, and needle jet. the small piece your talking about (about the size of a tic tac) is the needle jet. i don't see how this piece could break. it is not held on to anything or screwed in anywhere. the needle goes between it. the piece right below it that holds this jet needle up is the needle jet holder (#24). the needle jet holder screws into the carb and is tightened down by a nut. the mainjet screws right into the needle jet holder.


with your mods and elevation, i would run a keihin 155 mainjet, needle clip in stock (3rd) position, 40 pilot jet is fine and 2-2.5 turns out on fuel skrew.

if something is broke on the carb, fix it. i have a feeling your talking about a different part than i think but who knows.