 1989 H1 Introduction model
1990 H2 Changes to swingarm, curved radiator replaced flat one, rest of bike unchanged
1991 L1 New Frame and Engine Changes.Fairing changes included single headlight unit
1992 L2 
1993 L3 
1994 L4 Limited edition ITOHAM Scheme
1995 - 1999 L5 
1999 L9 Modified engine internals

Both the L and H models were produced in a very limited "Sport Production" series, allowing Kawasaki to homologate a higher specification to make them more competitive in the Formula 3 race series, and were only available in Japan.The H1 Sport Production model was known as ZX400J1, and the H2 equivalent was ZX400J2.The L model dropped the "Sport Production" decals and instead had "400R" on the number board, and was simply known as ZX400M.These models are identified through the VIN, which begins with the digit 3.