i have a 2006 z400 and it makes good power runs great but mine makes a funny noise on the left side of the motor when your sitting down. it only makes this noise when im really reving it up when ridin or right after i let off after high reving so that counts out the actual chain drive because it wouldnt matter if it was reved or not. i meet some guys up in tenn and they said that the timing chain was the first thing to go in z400s. anyone know?

 

better have it chkd out we are still running the factory chain on ours. last year we installed hot cams and the chain and guides were in great shape

 

you need to pull out the "automatic cam chain tensioner" and see if it has any adjustment left. It is a spring loaded shaft with notches on it and if you are down to only 2 or 3 notches left you will need a new chain.
I did my 05 a couple years ago and did the 04 about a month ago. They stretch and get noisey.
Let me know if you are going to do it yourself and I can point you to a thread that explains it pretty well.

 

alright thanks spize909 thats what i needed to know and yes ill do it myself so can you tell me that thread

 

this should get you there........
Replacing Cam Chain - SuzukiCentral