My brother in laws 2002 400ex seems to have a lot of trouble starting when its cold. He has to full choke it and then give it some throttle to get it to start. Now mine just cold starts with the full choke on??
Then move it to 1/2 after about 30 seconds and off after about 1 1/2 mins.

Any ideas what might be causing this??

 

Don't worry all new Hondas are cold-blooded when they are new. You really have to be careful warming them up when they are new. Try not to give them that much gas when you first fire it up. You might want to raise the idle a little bit so it will idle on it's own when the choke is in the middle.

I think what causes this is that they are jetted either too rich or too lean from the factory. Also the cold weather doesn't help with the new motor.

Try this, when you go to start the motor when it is cold, put the choke all the way up and hit the starter button. When it acts like it is about to turn over give it a little bit of throttle and just hold it there at low rpm's but enough to keep it running. Do this for about a minute or two. Then, while still giving it a little bit of throttle, turn the choke to the middle position and let off of the throttle. Just let it warm up for a few minutes without giving it any throttle and let it idle on it's own. Once again, you might need to raise the idle a little so it will idle on its own. Then turn the choke off and jump on and ride.

I would suggest trying that for about the first 10 hours of riding or the first 5 tanks of gas. Then it is due for it's first tune up. Take it to the dealer and have them set the valve springs, change the oil and filter, and whatever else needs done.

I hope this helps you with your new 400ex. If it still will not start, or your constantly fouling plugs, try spraying some engine starting fluid on the spark plug so that it will ingite better. Thanks.

Fourtracker14

 

Cool thanks... yeah mine runs fine, but his just doesn't seem to want to start without a little throttle and full choke..so it must just be the new bike thing..thanks

 

i just quickly pump the gas once or twice. if i give it gas while i hit the start button i will get no where. i will just flood the engine. mine seems to start in the cold on full choke if i quickly hit the gas once or twice then let off and hit just the start button.

 

thanks for answering a concern of mine also. I have a brand new 2002 Honda 400ex that is about a week old and it is having the exact same problem starting in cold weather. I've been doing exactly what fourtracker14 says with a little throttle to keep in running but not rev the engine. I know when an engine is cold, the oil is not circulating 100% and that is not the time to rev the rpm's high. thanks

 

Deathbringer -

Your brother-in-law needs to make a simple adjustment. Honda jets their machines lean (even says so in the owner's manual).

He needs to turn the air/fuel mixture screw 1/2 to 1 turns out. It is located under the carburetor, right in front of the floatbowl. Do not adjust the idle, it only masks the problem. Think of the air/fuel mixture screw as a fine adjustment to the pilot jet.

See my other posts regarding this:

post 1

post 2

ogre

 

Usually if i know im gonna be riding in cold weather, i throw a space heater on it for a little while. It warms the engine, and it always starts right away. Just my 2 cents.

 

this is what I do
pump the gas 5 times
start it
as soon as it starts ride it in first for about 30 seconds
mine will idle fine then

 

Mine was the same way. I have improved it by doing as Ogre says and adjusting the mixture screw. It helped noticeably. I also pump the throttle about 5 times before I even hit the starter button. I have never flooded my 400EX. I have had it for 3 years.

 

A #42 pilot jet will cure your problem. As it did on mine. Mine lights right up and idles fine.