As mentioned elsewhere, the radiator can be a weak area. There don't seem to be any off the shelf stone guards so the DIY route is the best option.

[[https://www.apriliaforum.com/forums/member.php?112725-glopro|Glopro]] used this soltion [[https://www.apriliaforum.com/forums/showthread.php?352563-radiator-fan-mount-wear&p=4595267&highlight=cheapo+Chinese+rad#post4595267| Cheap Chinese Rad Guard]]

He has since pointed out the one he ordered was no loner available and this [[https://www.ebay.co.uk/itm/Motorcycle-Radiator-Grill-Grille-Guard-Cover-for-KAWASAKI-650-Z650/174083172926| one for a Kawasaki]] should be tried instead.

Alternatively, some chicken mesh, a bit of car window seal strip, 3 screws. And Bob's yer uncle. [[https://www.apriliaforum.com/forums/attachment.php?attachmentid=144542&stc=1&d=1282128371|DIY Rad COver]]