Well i want to start by saying i am new to this site but not to thumpers.I have a 98 yz 400. don't and never really had any problems with this bike but like i said im new to this site and have seen some mods talked about (BK) & (blue wire) im sure if i had time i could learn more about these but time i do not have right now. just wondering if some one had a few minutes to explain to me what these mods are and why they are done? like i said nothing wrong with my bike starts cold or hot has since it was new in 98 but if i can make it even better bring it on.As soon as i get more time i will look over every thing here real good but for now any help with these or any other mods for this bike would be greaT!!! oh by the way great site can't wait to sit and look and learn more thanks MUD RULES!!!!