Problem with engine || Strange sound when clutch is pressed

[ClintBarton]

HI,


I have some problem will my bike (XTREME) which mechanics are not able to diagnose properly.My bike runs fine when I'm driving it below 40. At top speed like 60 -90, My bike is also running smoothly. but when I press the clutch for 3-4 seconds. then strange (khat khat ) sound comes from my engine and after releasing clutch the sound goes any.Initially mechanic told me that chain is loss but after replacing the chain pocket, the problem still persistedNow mechanic is telling that valve might be bent and he will open the engine... Please help

Please help.

I did not find the right solution from the internet.

References:
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Thanks!