400ex keeps cutting off, help

[big_poppa49]

Well after cleaning out my carb from where it has been sitting not being rode for almost a year, I got it to run but it keeps cutting off when I come to a idle. I know nothing about carb adjustment but if somebody can point me in the right direction would be greatly appreciated. I have never touched any screws on the carb since it was brand new in 01'. I also just put in a new spark plug.

[Rip_Tear]

First suggestion is to check the idle screw and any other adjustments easily done on the carb, maybe it accidentally got moved.

Stock is 2 and 1/4 turns out (counter clockwise) from tight, do not use much force, it should be relatively free moving. I do suggest you go through everything you did when cleaning it first though to make sure there doesn't seem to be any problems in the carb.

[Thumpin440ex]

Try to give it some gas when coming to the stop and see if this helps. Is the bike idling fine once started in idle? Can you shift the bike from neutral to first while the bike is running with out it stalling ?


John

[big_poppa49]

rip_tear, which screw is my idle screw? Can you describe it a little to me?

Thumpin, if I come to a idle and give it some gas, once it revs back down it will still cut off. It will stay running while driving and on the gas, but I will say that it does not run completely smooth. I will have some sputters here and there

Please note when I done my carb clean I took tank completely off and dumped old gas as much as I could and filled with fresh High test gas. (premium)

[storms400ex]

did you take the pilot jet all the way out and make sure all the holes are open???????

[CJM]

You gotta take the carb apart and spray carb clean through the jets..

[DragonGunner]

Originally posted by CJM
You gotta take the carb apart and spray carb clean through the jets..


This^^^^ and take out your floats and clean, and your air mixture screw and spray in there too....get it all and might as well take apart and clean the accelerator pump while your at it.

[Rip_Tear]

The arrow on the top right of this picture is pointing at the idle screw
http://www.atvriders.com/images/articles/pilotjet/pilot1.jpg

If this doesn't help the idle problem you definitely need to look into your carb before something happens, it may just need a cleaning even running a kind of carb clean in your gas may be enough to do the cleaning.

You should also check your air filter and snorkle and make sure it's getting enough air and there is no blockage.

[jman7290]

Definitely sounds like something is still cloged. I also take torch cleaning tips and push through the holes in the carb and the jets and spray with cleaner.

[Thumpin440ex]

Yeh, take the float completely out, clean the float seat, needle. Def still sounds like a fueling issue in the pilot circuits


John

[big_poppa49]

tried turning the idle screw with no luck. This thing still wants to cut off. Even while riding it backfires alot and just as soon as I pull clutch in it shuts off.

So you guys think something is still in the carb? How do I take the float off?

Basically, what all can I take apart on the carb and clean? I did clean the jets, I shot it with carb clean spray and took compressed air and blew them off good. Thats all I took off though. I did not take floats or any other part off

[CJM]

What jets are in the quad? Id say you should have a 38 pilot (stock) and a 148 main if its still stock.

Most switch to 42 pilot and 155-160 with any sort of exhaust or intake mods.

Take the float apart and clean the float needle.

[big_poppa49]

I have stock jets, I have never changed them. As far as exhaust I have a Yoshimura slip-on, but its not a full system.

Do you think I need the other jets you said?

If so, can u link me to them?

[CJM]

Shouldnt need them, always a good idea of course.

www.jetsrus.com

[Thumpin440ex]

I can agree with CJM to a extent, if it ran before, all of the sudden won't run now after sitting, then seems it still is fuel related.. None the less a fatter pilot in it self is a nice upgrade over the lean one from the factory


John

[big_poppa49]

So your saying my stock jets is ok to use with my set-up but the Jets that CJM linked is a good upgrade, correct?

Yea I guess I still got a fuel problem somewhere. I guess I will pull carb again and clean more than what I did last time.

[big_poppa49]

Oops, CJM, you linked me to the site but I am lost as to which jets I should get.

Also, if I get those jets, would that be all I need to buy?

[CJM]

http://www.jetsrus.com/a_jet_kit_atv/honda_400_TRX400EX_1999-2008.htm

Buy a 40 and 42 pilot and 150-160 jets. This way your covered either way.

I still say you have a clog somewhere. Did you physically remove the jets and clean them? Remove the float and inspect the float needle for wear as well.

[big_poppa49]

I did remove the two jets and clean them. I did not remove the float assembly. This could be my problem as my problem with starting was the float was stuck and not letting fuel get into the carb.

I a little confused still on which jets to get. I only need two jets right? A main and a pilot.

I just want to make sure I get the right ones. I would like to have these jets on hand when I take the carb back off to clean the float needle or anything else in there.

You think I need a carb rebuild kit? If so, since I will be getting these jets you linked, I see that the rebuild kit comes with jets (stock), is there a rebuild kit that does not include the jets?

[CJM]

not really, all rebuilt kits basically come with the same basic parts. Stock jets, sometimes a needle, float needle, etc.

As I said earlier: buy a 40 and 42 pilot jet (slow jet) and a main jets of 150-160. Thats pretty much it. I would also replace the float needle using a carb rebuild kit.

For future reference-dont leave gas in the carb for long periods of time. it gums up everything as the gas goes bad. If your going to store it simply turn the small flathead screw near the bowl, it has a line on it that is a drain. Drain out all the gas and bingo your done.

[big_poppa49]

how do I get the float needle out?

I believe I will get those jets and a rebuild kit. That should fix her up.

[CJM]

When you get to the float, take a small punch or something similar like an awl and push the pin out. It can only really come out one way cause the pin has grooves on it. The float needle is attached to the float. When you take it apart you will see what Im talking about.

[big_poppa49]

CJM, im trying to be a pain in the butt on purpose, lol, but explain to me why you say to order (4) total jets? Im completely carburetor clueless and I dont know what each jet does and what changing one will do etc.

[JOHNDOE83]

Check out www.jetsrus.com go to the faq section and read everything on jetting and it will give you a better idea of why and what needs to happen.

When you add a exhaust and filter, you breath more air, when you breath more air you need more fuel to compensate or your motor will run lean and be less reliable.

Follow the instructions for main jet tunning at jetrus, youll also need to up the pilot jet. I have yet to need to adjust my needle, but many others have had to adjust it, as long as your not hesitating in the midrange or bogging down, the needle should be fine.

Plug reading is irrelevant and not needed anymore, in my opinion just ignore the plug reading section.

It may not seem like its right, but this advice is tested and proven many times over.

[CJM]

Using the link John posted, basically you keep adding jets which add more fuel till it begins to stumble.

The goal is to add the jet that gives you the most gas without stumble. Whenever you work on a carb it works like this: either you need more or less fuel depending on what you have done to the engine. Adding things like exhaust, higher compression etc you need more fuel to feed it.

Dont have enough fuel, specially on an air cooled engine like a 400ex-it blows up.

[big_poppa49]

Ok. I took the carb back apart today and removed the float and float needle. Everything appeared fine, I sprayed some carb cleaner in there anyway. Also took apart the throttle area, sprayed in there real good, took out both jets and shot them with carb cleaner and I can see light through all the holes also. Put it all back together and this thing still runs like crap. Backfires like crazy when revving. Also still cuts off. I tried turning the idle screw also, still a no go.

I will tell you this, it seems to run better with the choke on.

Is this all just a tuning issue or do I have another problem? Or do I still need to get a carb rebuild kit?

[CJM]

If it runs better with the choke on then its lean.

order those jet sizes I talked about and try putting them in there.

Did you notice the float needle, it has rubber on the end of it. Was it pliable and in good shape, not stepped and not hard?

[big_poppa49]

Um, I looked at it but didnt inspect it all that good. But I remember it having a bit of a hard feel. It was pointed and not 'steped' off.

Yea it ran better with the choke on, im not going to say perfect, but it would at least cut back on the backfire and drive around and stay running.