I bought a 2000 400ex december 26th, and it was fine for the first 2 weeks and then after that the chain started bangin off the swingarm skid, when im at low rpms it makes the chain jump really bad, it jumps up and down and hits the skid..i tightned the chain and it didnt help..im wondering if maybe it is somethin internaly maybe moving the front sproket..its very annoying and im worried it might be somethin major...once im at high rpms its fine but when i shift it does it for like the first few seconds then stops...if anyone can help it will be greatly appreciated...any additiuonal info let me know i can go into more detail if needed...thanks

 

you need to adjust your chain read the owners manual for instuctions chains stretch especially new chains.

 

Did the chain slip on the sprockets before you tightened it? What condition are the front/rear sprockets in now?

 

Do you know what u are doing? Sounds to me u don't. Just tighten it, or read the book on it.