Modern Vespa

My Rally engine makes a strange "rattling" noise at idle that goes away when pulling the clutch? The engine is rebuilt with new bearings, crank, vespatronic ignition + much else. The noise appeared after the first longer ride after the renovation. What can cause this noise? Unfortunately it seems to be impossible to add a video.

Upload to youtube and post the youtube link please.

Could it be that it's not in the engine, but something loose at some side of the clutch cable??

Upload it to YouTube then post the link here.

Here is the video. You can clearly hear when I am pulling the clutch.

https://www.youtube.com/shorts/oj1uaa4U3l0

Clutch or something clutch related loose or warn out. Pull, disassemble and inspect the clutch.

Clutch side crankshaft bearing warn out with too much end play. Check the end float of the flywheel - side to side movement. Push on flywheel and pull in clutch - feel for side to side movement.

Reading the first post before giving advice saves everyone time.

Pull the clutch cover off and have a look.

Obviously if rebuilding the engine was effective we would not be discussing this at all.

Not a clutch issue. Tight fit and woodruff key in good shape. The spacer is there. I guess I have to split the block.

Hold on now...

Let's spitball for a spell.

Longshot: Any chance the tag end of the cable is rattling against the block or rear wheel and when you engage the cable it pulls it off whatever it's rattling against?