Here is some info for you:
The CB750K1 Four was sold from 1970-71 and was available in one of four colors: Candy Ruby Red, Candy Gold, Valley Green Metallic, or Candy Garnet Brown. The gas tank stripe was gold. The tank, side covers, and upper forks were of the basic color (red, gold, green, or brown). The side covers were smaller and there were no slots on the leading edge. There was a two-throttle cable system (pull open and pull closed). The headlight shell was also the basic color. The exhaust system was a 4-into-4. The engine was a 736cc SOHC 2-valve dry sump inline 4 cylinder linked to a 5-speed transmission and chain drive. Honda CB750K1 Wiring diagram
Serial Number
Frame: CB750-1044650
Engine: CB750E-1044806
The CB750K2 Four was sold in 1972 and was available in one of three colors: Brier Brown Metallic, Flake sunrise Orange, or Candy Gold. The gas tank stripe was gold but as with previous models, the Gold tanks had a black stripe. The side covers were smaller than the K0 model and there were no slots on the leading edge. The upper forks were chrome. The headlight shell was black. The taillight and side reflectors were larger. There was a two-throttle cable system (pull open and pull closed). The exhaust system was a 4-into-4. The engine was a 736cc SOHC 2-valve dry sump inline 4 cylinder linked to a 5-speed transmission and chain drive.
Serial Number
Frame: CB750-2000001
Engine: CB750E-2000001
The CB750K3 Four was sold in 1973 and was available in one of three colors: Flake Sunrise Orange, Candy Bucchus Olive, or Maxim Brown Metallic. The gas tank stripes were white, gold and black. The side covers were smaller than the K0 model and there were no slots on the leading edge. The upper forks were chrome. The headlight shell was black. The taillight and side reflectors were larger than the K1 model. There was a two-throttle cable system (pull open and pull closed). The exhaust system was a 4-into-4. The engine was a 736cc SOHC 2-valve dry sump inline 4 cylinder linked to a 5-speed transmission and chain drive.
Serial Number
Frame: CB750-2200001
Engine: CB750E-2200001
The CB750K4 Four was sold in 1974 and was available in one of three colors: Flake Sunrise Orange, Freedom Green Metallic, or Boss Maroon Metallic. The gas tank stripes were white, gold and black. The side covers were smaller than the K0 model and there were no slots on the leading edge. The speedometer showed increments of 20 (i.e., 20, 40, 60, 80, etc.). The upper forks were chrome. The white tank pinstripe was wider than the K3 model. The headlight shell was black. The taillight and side reflectors were larger than the K1 model. There was a two-throttle cable system (pull open and pull closed). The exhaust system was a 4-into-4. The engine was a 736cc SOHC 2-valve dry sump inline 4 cylinder linked to a 5-speed transmission and chain drive.
Serial Number
Frame: CB750-2300001
Engine: CB750E-2300001
The CB750K5 Four was sold in 1975 and was available in one of two colors: Planet Blue Metallic or Flake Apricot Red. The instrument faces were dark green. The speedometer numbers were increments of 10 (i.e., 10, 20, 30, 40, etc.). The side covers were smaller than the K0 model and there were no slots on the leading edge. The upper forks were chrome. The white tank pinstripe was wider than the K3 model. The headlight shell was black. The taillight and side reflectors were larger than the K1 model. There was a two-throttle cable system (pull open and pull closed). The exhaust system was a 4-into-4. The engine was a 736cc SOHC 2-valve dry sump inline 4 cylinder linked to a 5-speed transmission and chain drive.
Serial Number
Frame: CB750-2500001
Engine: CB750E-2372115
