chad,
yep, it is really amazing what 1 size up in the pilots will do to the bottom end response, starting, & low to midrange..
and a valve adjust every so often..the starting problems on most things go away.. good advice..

 

I live in michagan by lake michagan and have a 2002 400ex that I race mx with and it starts as easy as can be all the time. Full choke and it starts.

 

they are impossible to start if you have the white bros rev box in

 

mine wont start with just the pipe on it!
stupid thing

 

StevieD, no offense, but if you can't get your spark plug out, it doesn't sound like you should be messing with your motor at all. Go to the Honda Dealer and get it tuned up. (New Plug, Valves adjusted, Oil and Filter Changed, Air Filter Cleaned, and Carburator Cleaned). You could have one of many problems.

1. Battery isn't fully charged
2. Spark Plug is Fouled
3. Starter Motor Burnt Out from holding the start button too long
4. Valves really out of adjustment
5. Dirty (or clogged air filter)
6. Stuck Float, Needle, or Clogged Jet in Carb (from gas going bad.....gotta drain that bowl if it's going to sit for more than a week)
7. Kill Switch on "OFF" instead of "RUN" .......(My personal favorite)
8. ANY COMBINATION OF THE ABOVE

While you're at the dealer, have them put in a bigger pilot jet, and spend 10 bucks on the factory tool kit with spark plug wrench. Have the service manager show you how to remove the plug. It's fairly easy.

I don't want to come across as a smart a$$, but if you're going to ride quads, you gotta learn how to troubleshoot and fix your own machine. Take care of it, and it will take care of you. So, take this constructively....not personally. Odds are, your battery isn't fully charged, or your plug is really fouled up from running way too rich.

 

Believe it or not....I had a 400EX that I ONLY rode in the winter. I went up 3 sizes on the main jet, raised the needle 1 slot(lower the clip), and put in a 42? pilot. I never even used the choke! Just pump it a few times before you fire it up.

 

LOL its kinda funny listn to you guys about the cold i live in northern minnesota its terrible here lol. i love my ex little hard to start in the winter but no prob when going its solid.

 

I live in Nothwestern NJ where we just got a foot of snow and my friends and i had a hard time starting our quads the first time........ its just a little harder to start any quad in the cold

 

I don't know if this has been mentioned, I didn't read all the post. I was having a hard time getting mine to start too. Take off your air filter and put your hand over the carb then try to start it. Mine started right up.

 

i have a 42 pilot jet in and i could not tell a difference with it and the 38. yes i do pump the throttle a few times and it still won't fire without the choke why? i don't know. maybe i need to come out on the skrew a 1/2 a turn or so. as for the needle, did you notice a difference in power when moving the clip down one position? i have a modded air box and a gutted stock pipe and i thought about doing this but i did know if it would make a difference. i thought at least in winter it may make a difference by making the bike run a little more rich. thanks