I have 4 x 40mm 5 port cylinder barrell kits complete with matching windowed pistons, shamfered rings, 10mm pins, clips ect. this head kit is suited to all owners of samauri and other types of bikes fitted with the 40cc engine along with the 10mm x 32mm stroke crankshafts. this type of modified cylinder is very popular in u.s.a. and results have shown rpms of and above 13,500 rpms, these complete & ready to bolt on kits are now available at a price of only $40 each. contact RD Racing for any info on these.