Generation 1 (1987-2007) 
KLR650-A: The "A" model was introduced in 1987, based on its KLR600 predecessor (1984 to 1986).
The "A" model remained nearly unchanged until the introduction of the 2008 model in USA, Canada, Australia and South Africa.
It is not sold in Europe due to emission regulations.

KLR650-B or Tengai: The Tengai got Adventure/Dakar styling, a full fairing blending into the tank, different sidepanels, and an unsprung front mudguard.
It was sold in the US starting 1990 and in other countries for two years afterward - this could be classified as a separate model in its own right as the others are more trail bike orientated.
Its name "Tengai" is a traditional Japanese saying which means "The End of The Sky."

KLR650-C: The "C" model gets completely new bodywork and is a more dirt-oriented motorcycle fitted with stiffer 41 mm (1.6 in) front forks, improved brakes, tubular engine guard, smaller 14 l (3.1 imp gal; 3.7 US gal) fuel tank, and steel wheel rims.
Lacking a temperature gauge, it has an over-heat lamp.

The U.S. Military has KLR650s modified by Hayes Diversified Technologies to burn military-spec fuels including diesel. (
M1030M1) All-new engines were designed to replace the 4-stroke gasoline engines.
The new engines employ the original unit-construction main cases and transmission, but with new piston, cylinder, and other components.
The balancing system that is used in the gasoline KLR650 engines (to reduce engine vibration) was removed from the military diesel KLR engines.
Some components of the military diesel version can be applied to "civilian" KLR650 models, such as the nonspillable absorbed glass mat battery which offers several advantages over the conventional unsealed KLR batteries.

Generation 2 (2008-2018)
KLR650-E: 2008 was the second major redesign of the KLR650.
The changes include upgraded 41 mm (1.6 in) forks, a new D-section swingarm, dual beam headlight, dual-piston front and rear brake calipers, upgraded cooling system, 4 mm spokes, cowling and fairing redesign as well as various redesigned parts.
Generation 1 (1987-2007) 
KLR650-A: The "A" model was introduced in 1987, based on its KLR600 predecessor (1984 to 1986). The "A" model remained nearly unchanged until the introduction of the 2008 model in USA, Canada, Australia and South Africa. It is not sold in Europe due to emission regulations.
KLR650-B or Tengai: The Tengai got Adventure/Dakar styling, a full fairing blending into the tank, different sidepanels, and an unsprung front mudguard. It was sold in the US starting 1990 and in other countries for two years afterward - this could be classified as a separate model in its own right as the others are more trail bike orientated. Its name "Tengai" is a traditional Japanese saying which means "The End of The Sky."
KLR650-C: The "C" model gets completely new bodywork and is a more dirt-oriented motorcycle fitted with stiffer 41 mm (1.6 in) front forks, improved brakes, tubular engine guard, smaller 14 l (3.1 imp gal; 3.7 US gal) fuel tank, and steel wheel rims. Lacking a temperature gauge, it has an over-heat lamp.
The U.S. Military has KLR650s modified by Hayes Diversified Technologies to burn military-spec fuels including diesel. (M1030M1) All-new engines were designed to replace the 4-stroke gasoline engines. The new engines employ the original unit-construction main cases and transmission, but with new piston, cylinder, and other components. The balancing system that is used in the gasoline KLR650 engines (to reduce engine vibration) was removed from the military diesel KLR engines. Some components of the military diesel version can be applied to "civilian" KLR650 models, such as the nonspillable absorbed glass mat battery which offers several advantages over the conventional unsealed KLR batteries.
Generation 2 (2008-2018)
KLR650-E: 2008 was the second major redesign of the KLR650. The changes include upgraded 41 mm (1.6 in) forks, a new D-section swingarm, dual beam headlight, dual-piston front and rear brake calipers, upgraded cooling system, 4 mm spokes, cowling and fairing redesign as well as various redesigned parts.
Kawasaki KLR650