Lexmoto Adrenaline engine making rattle metal noise

Hi,

My first post and hope you kind people can help.....

I have a lexmoto adrenaline 125cc and i was riding along and got a false neutral chainging through the gears and the bike bike cut out slowly as i got into gear and died. I got it home and the bolt that secures the tapit for the exhaust valve had craked in 2 so i replaced that and done the valve clearances and now it makes a low metal ting noise. No idea what it is. The bike now struggles to start it takes a few attempts and seems to be running a little rich and a bit of smoke now coming from the exhaust. any idea guys.... i checked the cam chain tension and all seems correct. heres a video.

https://goo.gl/photos/QeU5o9TeKLjLdJJK9

Hard to say, when you have dozen things that can rattle.

I would do some disassembly, just to be sure.

I think I have it sorted. Pulled it apart and looks like the exhaust gas valve is bent. New bit ordered so hopefully that might help

Don't forget to do some valve lapping afterwards.

I don't know why, but looks to me that people lateley somehow are forgetting to do that.