i bought a 400 ex like a month ago it has a 440 big bore kit and some other minor stuff done to it...its nasty fast but only when it runs this is the second time this thing has left me sittin in soup gettin towed......anyways it runs like a dream for about 45minutes strong as you want it to be then some then out of no where it just shuts down and will not start again til it feels like it...we got it running by pure luck the first time and no such luck this time.....anyways its not throwing any spark it will just sit there and crank til the battery dies which takes like 3minutes! then about a week later it will start producing spark again any ideas? i mean this thing has me to the bon fire stage...........


thanks
Steve

 

Sounds like your CDI.
You probably need a new one, it is located under the front plactic mounted to the frame.

 

starting issues!
Please help. I have own a 01 400ex with the 440 big bore kit. when i first bought it i had the starter rebuilt because it was missing. it worked great for my weekend on the bike. now i'm having the same issue, the starter will spin but won't egage to crank over the motor! how can i solve this prob nice weather is here and i suffering from brap with drawls