Modern Vespa

I can't find any leak on my lml. I check everything but can't find the leak that causing the lean condition.

Symptoms:
-hard to get engine rev from idle
-back fire while going downhill
-noticeable lost on engine breaking


I test every possible leak between carburettor and the engine, float level, clean carburettor, valve gap adjust, every thing.

I need help...

Try Modern Buddy forum they have a Stella section or on fb in the UK there is the lml auto group.

Here's a link but if that fails it's called LML AUTO OWNERS.
https://d.facebook.com/groups/1536747986509729?refid=18&_ft_=qid.6889182065113021909%3Amf_story_key.1679452808905912%3Agroup_id.1536747986509729%3Atop_level_post_id.1679452808905912%3Atl_objid.1679452808905912%3Acontent_owner_id_new.100000175712101%3Apage_id.1536747986509729%3Asrc.22%3Aphoto_id.4015128101836341%3Astory_location.6%3Astory_attachment_style.photo%3Afilter.GroupStoriesByActivityEntQuery%3Atds_flgs.3%3Aott.AX8yC7bxOaabVHOK&__tn__=C-R