Kawasaki G31M

The Kawasakui G31M (Centurian) was a 100cc off-road motorcycle manufactured by Kawasaki from 1970 through 1971.

In the early 1970s the highly tuned G31M was a dominate force in Flat Track, Tourist Trophy and some motocross racing along with its larger brother the 250cc Kawasaki F21M. This model consistently dominated the 100cc class with its unheard of 18.5 horsepower rated engine. The small tip on the expansion chamber gave the Centurion a distinct sound that is unmistakable to this day. Only 4490 units were made in 1970.

Specifications

100cc
2-stroke, 1 Cylinder
Rotary Disc Valve (all steel disc as opposed to pressed fiber}.

G31M Crank Assembly

Rotary Disc Valve (steel instead of pressed fiber - original part #12001015)
5-Speed Return Shift
Maximum Horsepower: 18.5 HP @ 10,250 rpm
Spark Plug: NGK B9HV
Tire Size
- Front: 3.25-18 4PR
- Rear: 3.25-18 4PR

Color
- Fuel Tank: Lime Green
- Front Fender: Aluminum
Engine No.: G31E00001-
Frame No.: G31-00001-
Parts Catalog No.: 99995- 113 plus 99995-175S
Shop Manual No.: 99995-201 (SM-1)
Remarks: Motocross type version of the G3TR. The carb cover on the 1971 Centurian had an air filter unique to this model allowing extra air intake.