Modern Vespa

Can I do this procedure without special Piaggio tool?

Are you referring to the nut on top of the headstock bearings???

I think yes.This is the tool I doesn't want to buy.

I don't recognize that part, but I've never owned a Yourban.

No need to buy or pay the crazy prices of the Piaggio tooling.

Buzzetti makes very high quality replica tooling for a fraction of the price

I suspect you are looking for this

https://www.easyparts.nl/Balhoofd-Schokbrekersleutelset-BUZZETTI-universeel-verstelbaar-p33535870

Those are just weird shaped "C Spanners". Might be designed to go into somewhere difficult to reach with regular tools to torque rings.

https://www.amazon.com/dp/B07GDC41ZD

These are often used to adjust the retaining rings for rear shocks.

neither one of those look alike tools will allow you to use a torque wrench like the oem piaggio tools.

I think the same, none of this tools can attach torque wrench, maybe I need to modify some tool.

here is the part number for the piaggio tool, only $105 thru AF1racing.

https://www.af1racing.com/020892Y-OEM-Piaggio-Front-Shock-Adj-Key-for-MP3---020892Y

you would probably spend more time and aggravation trying to modify those generic tools and still not be good than just buying a set . Just saw some on eBay out of italy and I would go that route and just send the seller an offer and see if they accept it. worse they can say is no or counter offer.

That's very good idea.I would try it.