Here we have a CTC Yamaha TY250Z replacement chain tensioner kit, this replaces the discontinued Yamaha part number 4GG-22179-00.
This chain tensioner may need some minor modifications to fit into the TY250Z swinging arm but we have used them in the past with great results. This comes with an enclosed chain tensioner pad and new tensioner spring as in the photo.
This part used to cost £174.77 when it was still available from Yamaha.