2002 400ex jetting carb?????????????? help please!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[big bub]

i need help i am jetting my carb and i am i first timer
i have a 2002 trx400 ex white bros ex k&n filter and K&n filter box lid the pipe is a slipon
can anyone help me get close it

i am @ a 165 main jet stock pilot jet and moved one up on the needle clip pops 1/8 to 1/4 throttle and is hard to start till it gets warmed up
also i am 2 1/2 turns out on the carb
can u help www.juststuffinc@yahoo.com

[ti2ibal1]

I would say you are way to rich on the main. I would go with a 155. Stock pilot should be fine.

These machines are real cold blooded, so it takes a little "work" to get them warmed up. That's a given.

What problems are you having, specifically?

[rcatvrider]

I may be wrong but I'm pretty sure 1/8 to 1/4 throttle is the pilot jet or needle. I'd say the pilot is too lean if it's popping, but a 165 main is probably too rich.

[hornetgod13]

Mid-throttle is lean.

The clip should be on the 4th slot DOWN from the top. Sounds like you went the wrong way with the needle setting.

What size pilot jet do you have installed? Should be atleast a 40K if not a 42K. If it won't idle, than it's probably a combonation of incorrect pilot jet, incorrect fuel screw setting, and or low idle speed.

[Thumpin]

A year ago I got my 01 400EX and it came with a White Bros slip on and a K&N filter It was a bear to start no matter what the temp was. So I did my research online and found out how lean these sport quads come from the factory. Awha the pilots in these things were too small from the fatory for us people in the lower elevation!

So I ran stock on fuel screw(think it was 2 1/4 or 2 1/2 out), a 40 pilot, stock needle setting (3rd clip from top), and the k160 main that was in it seemed to always leave my plug black. I than changed it out to a k155 and it was spot on with the lid off.

After spending some time on here I ended up building a 416cc engine so my jetting is way different now. I also found dirt inside of my intake boot running a fairly new and always oil K&N filter with outerwear. I now run a UNI filter with outerwear and have no probelms anymore with dirt in my intake. And it seems to be close powerwise with the UNI.

But for your stock 400ex with slip on and K&N filter with a K&N lid you should be at the same specs I mentioned above, if it don't work, you got some other problems. Maybe valves need adjusted, could be a float problem in carb, dirty air filter ect?

2 1/4-2 1/2 fuel screw, 40 pilot, 3rd clip down on needle, K155main, and run your idle a little faster, helps at startup and warm up.

Mine now with the choke removed, I just pump the throttle 2-3 times and just crack it open a little and it fires and runs great, I keep it running for a minute or two and than it runs on its own. After that first fire up it will start with just hitting the start button.

Sorry this was lengthy but sometimes it helps someone to hear other peoples stories with the same problems, good luck!

[sc400ex_rider]

the stock pilot jet is only good if you store your quad inside your house. they are jetted very lean from the factory for emission purposes. a bigger pilot is the very first thing you should do to the ex even if it is stock!!! you will toast your battery cranking it every 5 seconds for 10 minutes

[400ex monster]

155 sounds good Im running that in my 04