Honda cb150f clicking sound from engine after first tuning

[captain.wave4]

The clicking sound starts when it gets hot after running a few kilometers.
I went to their workshop and one mechanic said it's nothing. I asked him to check the tapets. He said I loosen them at tuning and it is better this way.
I asked if it's according to Honda's recommendations? He said we lose a bit more.

Another mechanic said it's coming from clutch.

There was no sound before tuning.

[Hassan1991]

He messed with tappets. Get them checked again.

[captain.wave4]

Thanks for replying.
He said the bike is in running and the tappets need to be loose. Don't worry. The bike has different sound when it gets hot.

I don't know what millimetres Honda recommended for tappets.
BTW what's the reason that the sound comes only when it gets hot?

[Hassan1991]

Metal expands on heating.
You should search the stock gap between tappets.

[walana2000]

The same happened to me. before tuning everything was good after that there was a constant clicking noise from the engine. they mess it up now what to do. did you find any solution and what is the stock valve clearance gap. i couldn't find it in the owners manual