i need some help. please, im a newbie

[jaredhuth]

Hey guys I'm new to big quads. I had a lt250 and now I have a 2002 trx400ex. The only upgrades on it are a white brothers r4, race cut meyer plastics and moose bars. When it gets to running temp, and I go from about 3rd to stop it firs on me almost every time. I have to keep it reved to keep it running. Idle seems like it is really close to stalling also. Any advice?

[beags86]

is it jetted?

[jaredhuth]

I hate to sound stupid but I don't really know what that is

[brodzowski]

Originally posted by jaredhuth
and I go from about 3rd to stop it firs on me almost every time.

It does what to you every time? Backfires?

[jaredhuth]

Sorry, I'm on my BlackBerry so there might be misspellings. But in first if I rev it I backfires sometimes but I ment that it dies when I stop at like a stop sign and pull in the clutch. The rpms get really low and it stalls.

[hypersnyper6947]

the backfiring could be something different but as far as it stalling that could be as simple as turning the idle up a bit

[brodzowski]

There really are alot of things it "could" be, but I like to start with the easiest first and work from there. Most commonly a backfire when revving not under load is caused by an exhaust leak. Make sure the header bolts are tight and there's no air escaping there and where the header pipe meets the silencer make sure that clamp is snug and it's not leaking either. If those are all tight and good the next step I would do would be pulling the carb. Cleaning it might not fix it but it's a good idea anyway. While your in there check the numbers on your two jets. The pilot jet and the main jet. The low speed jet or the pilot can be too lean causing a backfire from what I've read. As far as your idle speed goes, how does it idle when you start it? Is it low too? If so, then you just need to adjust your idle screw out a little. If it idles fine and doesn't want to come BACK to idle after a load on it, that may be over my head, but it also could be due to that pilot jet. Lots of "what ifs" here.

[buster024]

Check these:

Make sure there isn't a blockage in the fuel hose between the tank and the carb. (it's a sizeable hose that connects from the backside of the on/off gas switch to the tank).

Make sure it isn't old gas. If it is, remove your gas tank, dump the old fuel, and replace with super unleaded.

Check your air filter, and long black filter boot for dirt, clogs, or excess oil. Upgrade it right away if it is a stock filter (k&n or uni-filters are the most popular).

After that, we are into cleaning the carb and re-jetting. Not a big deal on either. Just ask, or pm me or any of us for help on taking that stuff apart.

Just remember, it's rarely the first thing, but the more you dig into your bike, the easier it will get to diagnose these little things in the future. After your first time, removing a carb and rejetting is a 15 minute easy project.

[buster024]

is it jetted?


I hate to sound stupid but I don't really know what that is

Every bike has jets. They are small brass screws that have holes of various sizes drilled through them to allow gas to enter from the carb to the motor. There is a main jet, a pilot jet, a needle with a circlip, and a fuel/air mixture screw. All these things need to be dialed in to get the proper mixture of air and fuel into the engine. Every time you mess with that mixture (by adding an aftermarket pipe, filter, removing the airbox lid, elevation changes, weather changes) you may need to rejet to compensate for the changes. Typically, once you get the right combo for your bike, you won't be changing despite the weather or elevation, unless it is a dramatic change.

The bike comes pretty lean from the factory (jetting that doesn't allow enough fuel to get through). With the added airflow of the aftermarket pipe, the previous owner should have rejetted. If he did not, you may be running to lean.

[jaredhuth]

Ok ill check all that stuff. It idles low but I mostly stalls after I put a load on it. I just cleaned the filter and air box and everything. It also seems like I don't have as much power in like second gear. I will take off the carn tomorrow and take pictures and everything so I can get some help with it. the small length of exaust pipe from the header to the pipe itself seems loose on the pipe, like it would just slide out. I don't really know the best way to explain it. I will put up pictures tomorrow

[buster024]

the small length of exaust pipe from the header to the pipe itself seems loose on the pipe, like it would just slide out

Your exhaust pipe shouldn't be loose at all. No part of that bad boy should wiggle. That could very well be your issue. (along with the idle screw being to low).

[jaredhuth]

It has a very open pipe on it. It feels like it rides lean. I guess I could sort of tell that I'm not getting the response I should be getting when I let off the throttle. I was on the road and I kept stalling it at stop signs and its not because I don't know what I'm doing. Its just after I let off and pull in the clutch to stop it will stall

[jaredhuth]

Its not that it wiggles I took the pipe off and when I took out the bolt that held the pipe to the frame, it just almost slid off. And concerning the carb, do I take it off and rebuild it or just tweak the screw?

[buster024]

I kept stalling it at stop signs

We have four strokes, not two strokes. There's no need for that. Something's messed up. Make sure the exhaust is tight at all leak points, then let's get the carb removed to rejet. It's an excellent project to start with. Once you get it off, we can figure out what size jets you've got, and determine what you need from there.

Let us know when your ready to remove that, and we can walk you through it.

[jaredhuth]

Ok sweet. Thanks guys. I'm so glad I found this site. I will start tomorrow because I have nothing going on. So I don't really know how this works. Do I post pictures on this thread and will you guys get notified of it or do I start a new post or do I send a private messege to you or what do I do? Also, do you qant me to take the carn off? I know how to do that I just don't know how to jet it. Thanks again for everything

[0101]

You can just post the pics on this thread.

And welcome to the site!

[buster024]

Do I post pictures on this thread and will you guys get notified of it or do I start a new post or do I send a private messege to you or what do I do?

Just continue to post on this thread, and it will go to the top each time. Use the search feature as well. Every question has been answered at least 1000 times on this site, but don't feel bad asking, or there wouldn't be a site anymore.


do you qant me to take the carn off?

Yes, it would be easiest to at least get it free from the motor and airbox boot. You don't need to take the throttle cable off or anything, just get it to a point where you can turn it over and mess with it.

[81-Honda-04]

the bike might be dieing at stop signs even when you pull the clutch in if you arent shifting down and letting the rpms get way to low like you said. thats probably the easiest thing you can start with before taking things apart.
hope it all works out!

[jaredhuth]

I'm down in first before it happens. I checked that first. Ok so I have the whole carb off. I took of the throttle cable and all. Unfortunately my internet is down so all I have is my BlackBerry that means no pictures for the time being. Anyway what do I do next? Like I said the carb is off. Now what?

[zwark]

Originally posted by jaredhuth
I'm down in first before it happens. I checked that first. Ok so I have the whole carb off. I took of the throttle cable and all. Unfortunately my internet is down so all I have is my BlackBerry that means no pictures for the time being. Anyway what do I do next? Like I said the carb is off. Now what?

Take the float bowl off and unscrew the two brass jets. remember when you tighten them make sure it isn't too tight, since it is brass it will strip easily

http://www.atvriders.com/articles/pilotjet.html

[jaredhuth]

Ok so I'm looking at what I think is the jet and the only number I see is 148

[jaredhuth]

Ok so good news I cleaned the whole carb and there was stiff in it and I think that was why it was acting funny. I'm putting it together right now but I'm cleaning it too to bottom and clear costing the plastic to make it all shiny and new. Again thanks for all the help. There is still a leak in the pipes and ill post pictures where it is leaking on a new post.

[buster024]

148 is the main jet. It seems to be a bit lean, although I've got an aftermarket carb on mine, and I don't really recall what the jetting on the stock carbs (especially what they should be once an aftermarket pipe was installed). I'm running a 185 main jet, no airbox lid, with an aftermarket pipe, and I still feel lean.

[jaredhuth]

Ok well I'm going to put it all back and run it on the track. If I still feel lean then ill run a little bit bigger jet. its just all trial and error. What carb do you have on yours?

[Red02EX]

From what I have gathered from researching this site, you need to rejet for that pipe or you're going to do some bad things to your 400. Go to Jets R Us and order their jet kit. www.jetsrus.com

[DirtMonkey]

Also read the FAQ's there is a lot of GOOD info on that site and you can get a jet kit for 30 bucks ( JetsRUs)