i just got a 2003 400ex for christmas and it ran fine until the cold weather came. it has a K&N air filter and an LRD full exhaust and im pretty sure it has a jet kit. is there something wrong with my motor or does it just not like cold weather? thanks

 

Well it was about 20°F today when i was out riding and mine was running fine.

 

in what way was it running bad?

 

My brothers 02 400ex also starts very poorly in the cold. We had to pull it for about 100 yards to get it to fire the other day. Mind you it has a lot of time on it and it was about 25degrees F. The 1986 Foreman 350 (tow/snow plow vehicle) started in about 1 second.

After it warms up it will start fine. New plug is going in it, but he says the plug in it was installed about hafway through summer.

Any ideas are greatly appreciated.

 

well it just wants to die in the cold weather you just have to keep it like a quarter throttle until it warms up then its fine. but i havent had to pull it to start it yet.

 

Mine doesn't run well cold either, try to add a bigger jet and raise the needle up and let it warm up for a few minutes and make sure the carb don't have junk in it.

 

i think your pug is probly fouled if you have to pull start it. and also you cant use a regular plug wrench you have to use the one from your kit. i spent like an hour and a half trying to figure that out (this is the first honda ive owned).

 

put in a 40 or 42 pilot jet and that will help out. these bikes are cold blooded, but the pilot jet will help out. if it wants to miss when giving it gas, move the clip on the needle to the 4th position.

 

i would put another jet in but in oregon it never really gets to cold. but thanks for your guys hellp now i know it not going to like die on me

 

Hey oneten I am just up in Monmouth! Maybe we can hook up to ride sometime. I head to Florence 1-2 times a month. I had trouble with my 2000 400ex on Monday night. It was just to cold & I had a few issues contributing to it not running right. They all stemed from it being to cold. I made the mistake of leaving my bike outside in this cold weather. It was covered but was a PITA to start as all my stuff was frozen. I'm sure it's nothing major on your bike. They are a little cold blooded as stated above. After my trouble I put it back in my garage & it was fine the nex evening when I started it. Good luck