400ex stalling

[pepshocks]

just bought a 02 400ex, i had to put a new plug in it cause it was flooded out when i got it n wouldnt start. put the plug in n it runs now but keeps stalling out. this is bone stock-- stock exhaust, should i try turning up idle, or is this a jet problem, oh the filter is a lil dirty

[honda400ex2003]

i would start with cleaning the filter, carb, putting fresh gas in it, changing the oil, and such just for maintainance if anything else. it may have something in the carb that will cause it quit. at least that is my hopes. also do a compression test on it and see what it is. maybe it is time for a rebuild, should be around 120 psi. i would check out the idle, raise it maybe to spec and see how it is then. After this then i would start looking at spark to make sure it is putting out a good amount all the time, check the timing to make sure it is in spec and adjusted properly. lol you could have a days work in just getting it all setup and gone over to make sure everything is correct and ready to ride. this stuff should be done anyway just for reassurance while riding. steve

[pepshocks]

Thanks, I'm gona start Friday, il let you know how it goes

[clemsonteg]

I have an 07 I just bought for the wife that is having the same problem. I'm waiting for all my parts to come in so I can make some adjustments and clean it up a bit. I think it really sat for most of its life but I'm gonna throw in a 42 pilot anyways and the cable on the adjustment screw for the idle broke and the part hasn't even been shipped yet from bike bandit (won't order from them again) so I will have to take it apart again anyways next week if and when it shows up.

[pepshocks]

What size is the stock jet? N can u run any bigger with stock pipe? I know the bone stock 400's don't idle when cold but mine seems to be even when it's kinda warm it stalls

[honda400ex2003]

38 pilot and 148 main is stock with the f/a screw 2.25 turns out i think. it may be 2.5. It is hard to say what could be causing it to have issues once warmed up, someone will chime in though. steve

[f4iracer]

you just need to adjust the idle. If your idle speed cable is busted then a new one will probably help your problems. If not check your a/f screw. Mine would idle itself and slowly die when i had it too rich. Stock pilot jet isn't necessarilly bad once the quad is warmed up. It makes for hard starts but it will idle much better in my opinion.

[clemsonteg]

Well I found the reason mine wouldn't idle very well. I took it apart today to install a 42 pilot and an adjustable needle. When I went to adjust the F/A screw to 1.75 turns out to start I found out that from the factory it was only out 1.5 turns instead of the 2.25 it should have been. Either way I put in an adjustable needle from a pre 05 400ex on the 3rd notch and installed a 42 pilot 2 turns out with everything else factory all the way down to the exhaust and she starts up great with no choke.

[pepshocks]

Where's the f/a screw located?

[clemsonteg]

Its number 6 on the diagram below. If yours is a pre 05 then you can adjust it with a flat head screw driver. With the little experience I have you can't get to it with everything on. If you take off the plastics, the gas tank, and the snorkel then you can loosen the clamps and rotate it to the left and access the screw from the exhaust side of the bike.

http://www.bikebandit.com/assets/schematics/Honda/HJ1004034017.gif

[Wr3sTl3b0y]

any chance theirs marks on the timing chain to tell if its exact its been worked on recently a few times and its not starting for crap it starts but takes for ever may be off not sure

[honda400ex2003]

yup, there is a mark on the flywheel for TDC and a mark on the cam to show when it is level and in tme correctly. I think that there is a how to on the articles page on how to do it if you want to check it out. steve

[honda400ex2003]

here it is :D
http://www.atvriders.com/articles/valveadjustment400ex.html

it is pretty good to read through a few times and get it all set up. you wont have to adjust the valves but it is a good idea to also since you are going through most of the motion.
steve

[honda400ex2003]

also you would have to take the head cover off to check the cam lines. you would def know if it was not in time. it would hardly run at all if at all. lol. I would adjust the valves first and see if it helps it out at all. steve

[pepshocks]

i cleaned the filter n seems to be better, gotta let it warm up though, thanks guys