I just bought a new 03 400ex and yesterday was the first day of riding it. I drove the bike for one hour very easy because of the break in period(nothing past a quarter throttle). The bike was flawless, and after a hour of riding, I let it sit for about two hours to cool and I had plans to ride it for another hour. I had trouble getting it started the second time. The bike wouldn't keep an even idle with the choke fully open. I then restarted it and kept the throttle slightly down to help it warm up. I then would close the throttle half way and it would die. After a few minutes with this the bike finally started and I rode around for maybe ten minutes and it just died while I was riding in third gear. The bike wouldn't restart and I had to push the bike back about a mile to the house. I let the bike sit for about three hours and again it wouldn't start. Does anyone know what the problem maybe. It seems it could be running a little rich because the muffler was backfiring. Any suggestions would be appreciated.
-scott

 

Check the gas, you might be empty. Which part of St. Louis do you live? I am just west, St. Peters. Maybe It needs to be looked at.

 

I think just about every new 400ex owner has some problems keeping it running or starting it at first. I know that I did. What I have found that helps is to first read your owners manual, because it talks about this. Then, when you start it, hold the throttle about 1/2 way, with choke all the way on, hit the starter, and it should come to life. Keep your thumb on the throttle, and turn the choke off completely. The deal is, that you've got to sit there with your thumb on the gas for a while until it warms up. Since the oil is in a separate tank, it takes a bit longer to warm up. Once you get used to it, starting is easy. Alot of people will bump up their pilot jet to a 42. The 400ex comes jetted very lean. The increase in pilot size will give you more gas at idle, which will help you start and warm up faster. You just gotta remember to warm it up, and all will be fine. I know the second time I went to start mine, and it wouldn't I was very frustrated, but I got it all figured out and haven't had any problems since.

 

I also had the same problems when I first got mine. It was a pig to start when it was cold. I put a bigger pilot in and learned the technique that chad described and it now starts very easy. I would recommend going up to at least a 40 or 42 pilot. That will help a lot.

 

Hey, thanks for all the replies, I appreciate it. This is the first quad that I have ever owned, I do have to say, it is a pain to get it started. I did the thumb throttle(staying on it for a while) and it ran great yesterday after doing that. By the end of the day, I became use to what it takes to get it started. So my friends and I had a fun full day yesterday of riding around, until the deer hunters came out for their hunting at dusk. Tprender, I live in south county, but I ride over in MIllstadt, IL. MY wifes family owns land over there and we are able to ride, although I am itching to get down to St. Joes. Is it open year round? Again, thanks for all the suggestions, it really helped out.

 

Put a 42 pilot jet in and at the same time put a 152 main jet in and it will run a whole lot better. the larger pilot jet will take away the hard starting problems. You will find the colder it gets the harder it is to start.

 

I had a similar problem with my EX when I first got it. Play with the Idle a little. I had mine set too low... could be your problem as well.

 

sounds about right...
every 400ex does it.(p.s)why did u get the 400 ex.
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I got the 400ex because it is a reliable machine and should do me well for a first time owner. Oh, I looked at the z400, but there was a 1000 dollar difference between a new z400 and a new 400ex. IN addition, by the time you figure in the cost of a replacement for a bent axle on the z, then your looking at a larger price difference.

 

Congradulations on your new EX. I had the same problem with my bike at first. After reading the replies you got I have nothing else to add. My bike gave me problems starting for a while. Now it starts up right away. I don't let it sit for long periods of time without starting it. I try to start it at least 1x a week if I'm not going out on it. Also look up in your manual about using the choke too much. I remember reading that it shortens the life of the engine.

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