i have a 2001 400 ex. ive been having a hard time starting it lately even with the choke on. do i have to adjust the jet? or is it just the cold weather. i did hear the 400ex has a hard time starting in cold weather. thanks dan

 

The rule of thumb on jetting is, 15 degrees or 1500 feet elevation chang requires jetting changes, this doesn't mean this is your problem just a little tip.

 

gaff
that rule of thumb is a 2 stroke rule .
4 strokes are much differant ...
first you might try installing a new plug
second most 400ex's can handle a one size bigger piolt jet
on my 400 I can pump the gas 4-5 times and it fires right up (no choke) I live in minnesota and it get's -40 here and I dont even have a choke ....

If your plannig on riding in the winter months you might also want to raise your needle setting one clip ...(lower the clip on the needle raises the needle to richin it up )

also in the winter months it is even more important to let the quad warm up thoughly ....

good luck hope I helped

 

thanks guys, changing the spark plug does help but i shouldnt have to change my plug everytime i ride. are you talking about the main jet or the pilot screw. thanks dan

 

I was Talking about the main jet.
I as well used this as a two stroke rule of thumb, now it's all bikes.

Dan when you do get it started and warmed up, try adjusting your air/fuel mixture a little in then a little out. What you will find is the motor will run rough in and out, but thier will be a sweet spot in the midle, this will be the easyest.

Riding in the cold like you all do I haven't done for years, and don't intend on doing it ever again.

Now all I have to say comes from memory of living up north, down here, still 80 and cruising.

Good luck and have fun!!!!!!!!!!!!!1

 

the 400 at know for being hard to start. I do loike the other person said to do. Pus the throtle in a few times before I push the button. Then as I pus the button give it some gas and it should start. The 400 has a very stange starting rutine. We have found that it also help's to put in 1 or 2 sizes larger piloet jet. and this will help it start better in the cold weather. Rule of thumb on a 4-stoke is to change the plug once a year.

99 400ex stolen
2000 440ex

 

I have motor work done to mine.....I have to hook it up to a boost charger everytime I cold start it....or to a car....these motors are hard to get started, but run fine once cranked.

 

hello, thanks for all the replys. went riding today in 40 degree weather. pumped the gas 5 times with the choke on and it started pretty easy then quickly turned the choke off. that worked. after riding for and hour it would still stall out while idling. probably is the jet. never messed around with carbs before. little intimidated. thanks dan

 

hondadan

you might consider taking it to your dealer for a quick tuning
this problem your having is a lean condition and is not good for your motor. this will help you have a great quad for many years to come. You might also ask the dealer if you can watch him do it ? youll be suprized at how easy it is .....

 

I also just pump the gas 3 times(no choke) and mine starts right up. My 400 liked to die when idling until I backed the air/fuel screw(on the bottom of the carb, motor side) out 1/2 turn, now it idles fine. I raised the needle up 1 knotch, and changed main jet. One thing that surprised me, I had to go all the way up to a 165 main jet before the piston wash looked acceptable? It's about 30-40 degrees outside, I use the stock pipe and a Uni-filter. Did Honda really jet these 400ex's that lean from the factory, or am I missing something.