2000 Honda 400ex smoking

Hi i have a 2000 400ex Sparks full exhaust and jetted and it smokes a blueish smoke.

Why is this thanks A20

Sounds like its time for a new top end (piston, rings and bore the cylinder if needed)

sounds like you are burning oil to me

Have you over filled the oil? Is it smoking only when first started, during engine rev or all the time? Blueish color smoke is created by excessive oil going into the cylinder.

Try changing the oil and make use you use correct 4 stroke atv oil with all the additives. As oil breaks down, it can get past the rings into the cylinders. If it's excessive, maybe do a compression test.

* Added manufacturer to thread title.

Worn piston/rings, worn cylinder bore, or leaky/worn valves, seals, or guides can all allow oil to leak into the cylinder. Most likely you just need rebuild that motor. The more you can afford to replace, the better.