Hoping for a bit of advice, purchased a 2017 Cota 300RR this year and I notice it has a bit of a knock. I have several friends with Montesas and none seem to knock this loud. I have been told it's normal for them to knock a bit. I've checked valves and cam chain tension but it really sounds like a piston knock to me. I know she's got some hours on her. I suppose a video would be the best way to show you guys, I'll have to get one up here later on. I am concerned I'm going to damage something running it though, but I want to know if I'm going to need to do a piston soon. 

From everything I read these are not known for knocking or needing pistons, so I'm hoping it's just a normal thing. 

Take the spark plug out and alternately push down on the front and back of the piston with a plastic or wooden rod. If you can make the piston rock / click its probably going to need a new piston and possibly bore work as well. Certainly strip to measure.

Have you switched fuel type?  I haven't had a problem with running different octane levels in my 17 Cota 300RR but if your running the low stuff try higher octane or the other way around?
I don't really expect this to be the issue but at least something to consider?