I got on my quad a few days ago and it was a little stubborn starting but i got it and it would run okay until i tried to accelerate faster, then it would bog down and the engine would shut off.so i figured it was out of gas,so i swithced to reserve, and did the same thing.i finally got it back to the house and filled it up and it would not start now.When i push the start button it tries to start but nothing at all,not even starting for a second and shutting off.Do you guys have any suggestions on what this could be?I dont know what to do and i want to do whatever i can to get this thing fixed and ride again.

 

Alright,i fixed the problem,the spark plug needed replaced,it was all messed up.

 

I have an '05 400ex also, and i let it sit up for about a month and a half and what happened was the carb and cylinder was loaded with gas and so was the cylinder of unburned gas, and what happens is it floods itself out. The cure for this without having to replace the plug immediately is take the plug wire off and barely touch it to the terminal on your plug and hit the starter button and when you hear the spark make a pop noise and it busts off put the plug wire back on and hold the throttle at a decent rpm not screaming and let it run and it will burn the plug semi clean, enough to ride, but after that you can replace your plug or either clean it with wire brush to extend its life a little. This may take a few tries but it does work.

 

is there a way to get a 400ex to start withou a key(i can't find mine,im not stealing one.)