My name is Matias and i'm from Finland. I recently bought 1999 zxr400. The bike has 80k on the clock, it smokes black on +10k rpm and the timing chain needs to be replaced.
Black smoke could be from bad valve timing right? I'm going to take the bike apart soon, so what are the most important things i should check while replacing the cam chain?
Also to note, the bike has no maintenance history at all if you do not count the last chain/sprocket/oil chance which was marked to the bike's manual. Guys at the bike shop just said that the earlier owner had done all the maintenance by himself. I tried to contact him couple of times but got no answer.
I have checked the cam chain tensioner, and it is protruded to max.
But honestly from the looks of it, i can not believe that it has done 80k.
![Image](https://i.imgur.com/7MAScsz.jpg)