I have a 2004 yfz450 it has under 25hours on it. Last night i noticed a knocking sound coming from the motor what could it be. I know i am supposed to get the oil upgrade kit on these 04 models, and the decompression plug that i already ordered. What is the problem that would be making a knocking noise

 

It is an '04 and only has 25 hours on it? Could be valves need adjusting or the timing chain has stretched.

 

yeah it has very low hours it was rarely driven

 

thanks for the info, i was thinking it could be something with the crank too.