New Part # is N-MP-09517-1 (same part) (old part number N-MP-09516) 51mm 80cc 4 stroke GY6 80cc upgrade for 4 stroke Chinese 50cc engines like Schwinn 50cc QMB 139 includes head with titanium springs bigger valves more performance than 70cc kit. combines QMB N-MP-09517-1 and N-MP-095171-A