I have always owned 2 strokes and bought a basket case 400ex. finally got the bike all together. no big mods but does have a big gun slip on pipe. the guy i got it from said the main jet had been drilled out and no air box lid was ran on quad..

when i start the quad it takes forever to get it warmed up and will only idle. after about 10-15 minutes i can give it gas but it falls on its face and wants to die. every now and then it will run great and when i go for a ride it will go 25-30 feet and then cough and sputter again and start dying everytime i give it gas.. not to sure what to do now that this has me stumped.. it wouldnt run hardly at all with air box lid off but when i put lid on it would run when it wanted. almost acts like it is starving for gas, doesnt do any good when i turn choke on either.. if anyone has any ideas to what could be wrong with this i sure could you some advice.. thank you, jason

 

i would pull the carb off and give it a good cleaning,proper jet size and check the float and make sure its working right and adj right. i had a banshee that had miss adj floats and it would suck the carbs dry and the engine would fall on its face.

 

do u know what size he drilled the jet out to ? i think stock is .142 or .148

 

airbox lid off=more air
airbox lid on=less air

If it runs worse with more air
====lean

Richen it up