400EX won't start

[Chillyboarder]

Well I bought a 2001 400ex a couple weeks before christmas.
I didn't get it started until a week after christmas, boosted it from a truck and it started nice.
Now I have changed the oil, oil filter, and spark plug since then, and I was riding it every day for about 3-5 days. The next day I try starting it, it would start up and die suddenly, sputtering. Since then I have not been able to get it started, I have been told it could be ice in the carb. Though it wasn't cold that one night. And it started after 3 weeks of cold from a boost of a truck.
I have a booster pack (300amp) which I use everytime to give it the extra power to turn over in the cold.
I do not have the owners manual, though I can pick it up anytime if I wish.
I have instructions from Redrider_AK also for taking the carb apart.

I'd just really like to hear what you guys make of this, what could be the problem.
I'd prefer to know all my options before I tinker with anything, as this is my first quad, and I haven't worked on one before.

Also, I think it was 2 days before it wouldn't start, I had it stuck in a creek for over half an hour lol. It was very cold water though only about a foot deep. I don't really think that any ice or water from that could have gotten in. I also store it in a pretty much bare shed, has walls, a roof, but it's not sealed and the doorways are open. So it's cold overnight in it and will be to work on it. I have also tried water eliminator and gas line anti-freeze and was told to crank it or try starting it, to run the gas with it in it to the carb. Tried somewhat with electric start and go to try it the next day and jack all happens.

Here are the instructions RedRider_AK drew me up.
http://img442.imageshack.us/img442/2...uctionsak8.jpg

If I can think of anything else then I'll post it, ask any questions you may have.

Post all opinions and suggestions, much appreciated!

Thanks!

Hans

[ATC-Eric]

Hey Hans,

Start easy, pull the plug, keep it in the plug wire and hold it CLOSE to the head. Crank the motor and check for spark. If you have spark, then its like I suspect, you have a clog in your fuel somewhere, or water did get in your system.

I would go with spark real quick, because, well its quick and easy to diagnose.


If you have spark, check your fuel lines. If fuel is flowing freely to the carb through the petcock, then you need to pull the carb.


Its not that big of deal, just a couple bolts, and a little wrenching.

I would start by pulling the bowl, and just put some compressed air through the jets.

You'll be good as new in no time.

Good luck.

[TravEX]

What's the temperature outside when your trying to start it? They are infamous for being cold natured, I know this all too well! hehe.

A 42 or 45 pilot will help.

[Chillyboarder]

It's about -5 to -10, celsius, any colder and I wouldn't care to ride.
The guy had it stored for 4 months when we bought it, and he had to warm it up in his garage then boost it to show us. And for that next 3 weeks till I had a chance to boost it then it was fairly cold. But still started up nice.
It must've been -40 or so when we went to see the bike. (Had the previous owner take the test drive lol)

I can't take the plug out anytime soon, had to borrow the right wrench a while ago when changed it.
Hold it close to the head? If it's getting taken out of the machine, and still on the wire, I'm assuming the head is the top tip of the plug, then how can the wire only be CLOSE to the head?

The carb has so many things going to it though, I'm guessing at least 5 different hoses of all sort.

42 or 45 pilot, could you tell me what pilots are.

Also, would you know what would happen if I put TOO MUCH chemicals in, such as a fair bit of water eliminator along with the gas line anti-freeze.

[okieRrider]

These bikes are extremely cold natured. one thing you might look at if it was stuck in a a ft deep creek or whatever is the overflow vent lines that come off the carb and down in front of the swing arm. The machine runs on a gravity flow system so if the vents are clogged (with ice, etc.) it isn't gonna work. If they look all good pull the plug to see if it makes fire. I honestly think you have some bad gas, if so you need to pull the carb to clean it and drain the gas also. Lt us know what ya find. These things are pretty much bullet proof so this shouldn't be to hard.

[Chillyboarder]

Ok I went out and checked the lines, how will I tell if they're clogged? And is that the line going to the air vent system right up above the oil tank?
Yeah it had gas when I bought it, though used all of that within the couple days lol, and my dad had some in his shop so that could've been bad. Refueled before got home at gas station though.

[RedRider_AK]

If you put too much water eliminator, it will not want to run. I accidentally used too much Heet (isopropyl alcohol) in my Big Bear once, it wouldn't rev up and it would die unless I had it on full choke all the time.

[TravEX]

I bet it's just the cold naturedness of the beast shining.

Take the airbox lid off, spray ether or carb cleaner or something like that around the air filter. Pump the throttle about 6-8 times fully. Full choke. Then try the starter. Remember, when it fires up, wean it off of the choke ASAP. You WILL foul a plug on the 400EX in a matter of seconds with the choke on. You may have already fouled the plug. In cold weather I ALWAYS use a new plug to get it started. Even if it's a old plug that I know is good, it will get it started.

Try a new plug and things above and it will start. It takes a long time to learn the EXACT technique your 400EX will take to start in below freezing weather. This is the only complaint I have about my 400EX. I have had it 5 years and 8 monthes, STILL on the OEM battery, and I could still start it in below freezing weather.

Good luck! You'll get it.

[SmurfanCoke]

If you have a small blowlamp, try pulling the plug and heating the tip real good, stick it in, fire her up. I've had to do this a few times on my 420

[Jason Hall]

It looks stock, but Is It possable It has a aftermarket CDI box? I know the Whitebrothers CDI makes the 400 Start even harder that they normally do. They are VERY hard to start when cold, and as stated before every machine starts a little different. It might just take you a bit to figure out exactly what It wants to start easily. One thing to remember Is that a 400ex has an accelerator pump that gives the engine a shot of gas everytime you push the throttle. The accelerator pump can help with a hard starting machine and also make It harder because you could flood It. My buddy had a 99 EX with the Whitebrothers CDI, and he used to switch to the stock CDI In the winter because his was stupid hard to start when real cold. I have seen him put the stock CDI In to start the bike at our local Ice track warm It up, then put the aftermarket box In to race.

[Chillyboarder]

Yeah I'm not sure on the CDI. Coke's idea sounds most reasonable, if I can get a wrench for it then I'll try. How quick can someone foul a plug, I only just replaced it like a week after christmas.

[OldSchoolin86]

Yeah I'm not sure on the CDI. Coke's idea sounds most reasonable, if I can get a wrench for it then I'll try. How quick can someone foul a plug, I only just replaced it like a week after christmas.

Have you done the basics Like checked for spark, draining and replacing the gas, cleaned and inspected the air cleaner? Even if you have spark change the plug and make sure it's gaped per factory spec. The 400ex is NOT a machine that commonly fouls plugs unless you don't have the carb dialed in correctly but even new plugs can go bad. If you've done all that then take the carb off and clean it. You might have got something in the main or pilot jet. You should be able to see through them when held up to light. Also, if you do change the pilot do not go over 40 or 42. 45 is ridiculous, it won't help performance even if you had a 502 kit and will certainly make fouling plugs an easy task. The stock 38 pilot is fine for most applications.

[Chillyboarder]

It was a honda plug, NGK.
How do I drain the gas from the engine, fair bit of gas must be in there right, and that's the gas it'll use first. I'll replace the whole gas once find my problem and fix it.
Checking for spark I'll keep in mind as I said, but need the right wrench, only borrowed one last time.

[OldSchoolin86]

It was a honda plug, NGK.
How do I drain the gas from the engine, fair bit of gas must be in there right, and that's the gas it'll use first. I'll replace the whole gas once find my problem and fix it.
Checking for spark I'll keep in mind as I said, but need the right wrench, only borrowed one last time.

Doesn't matter what plug it was, it still can go bad. If you can get a thin walled 18mm deep well socket you can get that plug out. I took a normal one and ground it down to fit. Of course the stock plug wrench from the factory tool kit is best but I think mine is mid way up devils backbone. To get the gas out of the carb you turn the screw out at the bottom of the fuel bowl (on the carb). For the gas tank you can take the line off the carb and drain it out over night into a tub or bucket. The problem may be the gas, so waiting may not be the best idea.

[Chillyboarder]

Yeah I have to keep my eye out for one somewhere.

Akim told me the same thing about draining the carb, I don't get it lol. I see a bolt plug at the direct bottom, 17mm. No screw whatsoever. Akim told me it was supposed to be a bolt with philips head or so.

Would the "head" happen to be the inlet where the plug screws into, on the engine?

And man, with all the chemicals gone into this, and all the flooding I've probable done, wonder if it'll start when all the parts are fine even lol...