[Outdoorsmen]

Hi guys I have 2015 z force 800 it got a knock noise on engine it seem like on rear cylinder of engine I check valve ajustment and cam and timing chain all good pulled cylinder to check connecting rod don't seem like no play what could it be, the piston got a like scoring in the intake side of piston but not to bad I wondering where noise coming from. Any help would be appreciated

[NMKawierider]

In most all cases any deep knock is a rod..and even though it doesn't seem like it has play, many start by spinning the bearing first. If you have a sound clip of it.. post it. Piston scaring can be from many things including overheating (which is the #1 cause for bearing failure), particle ingestion or just using the wrong fuel.  Now that it's apart you are committed to a rebuild anyway so..

[Outdoorsmen]

It almost sound like it was in the rear cylinder or top end  not as much in the bottom end but u never know. I really hate to remove this engine and split it , I didn't remove the front cylinder it seem louder in the rear . I was listening it with a mechanic stethoscope,  I wonder if I drain oil and see if anything in it. The gentleman said had oil changed around every 3000km .