i have a 2003 400ex an randomly it wont get spark just turns over no spark i have replaced the coil the spark plug checked the wire harness an the fuse still nuthin any advice will help

 

How are you checking for spark? Or are you assuming because it wont start...that its missing?

 

take the plug out of the bike keep it in the coil an put it to the engine an turn it over

 

Is the plug cap loose? It will come apart if you pull on the cap, and maybe it isnt seated all the way.
Carry an extra new plug, and next time you dont have spark, try the new plug and see if it has spark. If it doesnt have spark either, its gonna be a loose connection, or faulty ig or kill switch. Does engine temperature factor in? Does it only do it hot? or cold?

 

Check your kill switch for proper operation.

 

i cant get it started at all it just turns over it worked one day then the next it didnt i have checked the wire harness disconected everythin an reconeceted it

 

Check the fuse?

 

fuse is fine..... when u have the key on an the switch off should it still turn over????

 

Which switch is off..the kill switch? The starter will still rotate the motor when, the kill switch is in the off position, and the starter button is pressed.
If the ignition switch is off, the starter motor should be able to turn.

 

i found out what it was it was my cdi box i had my friend bring his over just for the hell of it pluged it in an it started right up then i put mine in an it wouldnt start thanx for the help tho