Need an explanation..what's going wrong exhaust port

[ip_tune]

Hi guys..
Really confuse and no idea when see this at my RC390..
Whats going wrong? Odometer juz 18xx km..
Anyone also get this problem? and what the solution?

 

[Old3]

Stuck valve? Turn the engine over and watch for movement. Pull the cover off the head and check for carnage and valve clearances.

 

[ip_tune]

Stuck valve? Turn the engine over and watch for movement. Pull the cover off the head and check for carnage and valve clearances.

Thank you, i will check it out...