Racing Kart, Clone, Predator, Hemi, Honda, Briggs, BSP most Motorcycles or engines if they have a 4.5, 5, 5.5, 6,7 mm, 1/4 mm valve stem, If you are building or rebuilding your own small engines, either for performance or just a quality rebuild, this gives you control of cutting your own valve seats you can do a standard 45 degree seat or even 3 angle seat with this set… You can move the sealing surface on the seat for best performance… This is ONLY if you have 4.5, 5, 5.5, 6,7 mm, 1/4 valve stems this kit comes with the following. Valve Seat Cutter Kit Carbide Tipped 3 Angle Cut As Original Seat Milling In The Following Sizes 1st Top Angle & 2nd Base Angel Cutters Valve seat cutters: 22 mm 30 Degree & 45 degree 23 mm 30 Degree & 45 degree 24 mm 30 Degree & 45 degree 25 mm 30 Degree & 45 degree 26 mm 30 Degree & 45 degree 27 mm 30 Degree & 45 degree 28 mm 30 Degree & 45 degree 29 mm 30 Degree & 45 degree 30 mm 30 Degree & 45 degree 32 mm 30 Degree & 45 degree 34 mm 30 Degree & 45 degree 3rd Throat Angle Cutters 23 mm 60 degree 25 mm 60 degree 28 mm 60 degree 30 mm 60 degree 32 mm 60 degree 30 Degree & 45 Degree Cutters are Usable From Both Side As Other Side Is Grounded At 90 Degree.