Strange sound fresh rebuild ATC 110

[110atc1983]

Hi,
I'm new in this forum, last winter I started the project of rebuilding of old ATC 110 1983. The forum is very helpfull to trick or ideas. I finally completed the rebuild of the motor and the 3 wheeler. The issue of the motor was a bended valve. I started the motor couples weeks ago, but there is a strange sound at idle like a small bird."Quick, Quick, Quick"

Any ideas what could be the issue ?

Thanks for your help.

[kb0nly]

Did you set the valve lash and did you adjust the timing chain tension after you got it running?

[110atc1983]

The valve lash yes, but not the timing chain tension, any spec for that ?