i took my '04 ltz400 to a dealer ship a while back and they said a valve was going bad. since then i've noticed the performance has deceased. i'm preparing to change out the engine valves. i know there is an exhaust and intake valve, but is there just one of each in the engine? or are there more? i need to know so i know how many to buy. do you have any tips or suggestions before i take on the task of replace my engine valves?