My buddie just recently got an all stock 02 400ex and seems to have trouble starting when cold, when it does start it doesnt want to idel with a cold motor. It seems to idel and run fine once it gets warmed up. Ive heard that this is common with the 400's but we really want to get it running strong for spring, how have you guys worked this problem out??should we just run some carb cleaner through it??...
thanx for any input

 

well a little carb cleaner never hurts, so yes try a little of that. but the 400ex is a commen pain in the *** to start when cold. in the spring you shouldn't have this problem neer as much. i have an 06 400ex, and after my buddy recked into me.(bent axle,hub,rim,nerfbars,foot pegs,brackets) i let it sit all winter with out draining gas, or with out starting it. tryed to start it 2 -3 weeks ago while in the barn, and it gave me the big F U. put a heater rite next to the oil pan, for 15 mins. first push of the starter it fired rite up, then died chocked it then fired up and stade running till i shut it off!

othere then that if you know anyone that can take a carb apart have them take it apart and clean it! and new spark plug! and your buddy will be fine. it's a honda is-it-not! = ]

Let me know

 

Honda jets lean at the factroy, to meet emissions standards. If you are going to do any mods like an air filter, vent the airbox, or an aftermarket muffler, then just wait until you do those and then rejet it properly. If you are going to leave it stock and it bother's you that much, then get it rejeted.

Did you know you can adjust your idle??? You would be surprised at how many folks don't know this, and will sit there in cold weather babying the throtle on an engine that wants to die, when they could just turn up the idle a bit and solve their problem. It's just a simple turn of a ****. See your owner's manual...........

 

That doesnt sound like a problem to me thats how mine is. Why are you worried about it not running right when the motors cold anyways? And what i usually do to start it is just pump the throttle a few times and she starts up pretty easy.

 

The carb may be worth a look. There's no magic in there, by the way. With some pliers, a screwdriver, and some sockets you can take your carb into every piece it comes into and inspect it yourself. You should really buy a clymer's. (Mine fired right up in 25 degree weather, if that helps you gauge things.)

 

yea I think were deff gonna run some carb cleaner through it, see what happens... yea recon we've played with the idel screw in every way to try and get dialed in but didnt seem to help us much. And freerider its quite annoying when we try to ride but it takes us like 20 miutes trying to get the damn thing running right. We've tried pumpin the throttle and then starting it but still got the same stutterting and cutting out as we always do. We'll see what the carb cleaner and a new plug can do. thanx boys

 

a new plug will do wonders, also a valve adj, how long ago has it been? ahhh intake lash is .004 & exhaust lash is .005 if u want to check. mine has always been hard to start in the cold, when i lived up in indiana i started it all the time in the teens and bellow. oncei got it started i had to take off and ride a while, LOWEST RPMS possible, she's cold and the oil is so thick. after she warmed up idoled like a camp, and fouls out the plug:S mine runs rich but i like it that way. its a 400ex it will ALWAYS be harder starting than when its 60 out. my .02 hope it helps.

bowz

 

Your pilot screw on the carb... needs to be turned for it to idle at a higher rpm to stay started

 

Theres a few things you can try.
Check the pilot jet, to make sure its not partially blocked.
Check the setting of the mixture screw, and if its in spec,(2 1/4 turns out from bottomed) try another 1/4 turn out (richer).
Lots of guys change the pilot jet to a plus one(40), 38 is stock, and the 40 really wakes it up.
Use the choke for longer periods, until it doesnt pop back or backfire when going on the throttle.
check out this link In it they referr to using a 42, but if your motor is mostly stock, then 40 is more than enough.

 

im up here in canada and my ex is always a pain to start....so i just make sure i start it once every week...even if it meens killing the battery...and as long as u keep it started every now and then it will start in -26 conditions like a few weeks ago