1970 KAWASAKI G31M 100cc Centurion
By Matt Cuddy #MC1
The little green bike put out an unheard of 18.5 horse power at 10,500 rpm, and with its open foot long
stinger, and whooshing steel rotary valve, made quick work the competition, as no other 100cc racer put out
so much useable horsepower over such a wide rage. The bike had acceptable low end, the midrange was
excellent, and it had a big hit on top that just kept going until the power band signed off at around 12,000
revs. Kawasaki obviously had the rotary valve design down, as the little bike pulled like a strong 125 MX bike
on nitro.
The Centurion was first billed as a short track bike, like its bigger brother, the Green Streak, and made its
way into motocross competition with far better results than its larger sibling. Problems that plagued the 238cc
Green Streak didn’t manifest themselves in the Centurion, as the extreme light weight put less strain on
things like wheels, hubs and the frame.

The bike even caught the eye of Steve McQueen, who used the Centurion for back-lot duties, and
impromptu drag races with security guard golf carts. Of course McQueen painted it to look like a mini-
Husqvarna which confused fans to no end, most likely. It sold at auction in $55,575.00 in 1997.

Funny thing is though, a total of only 4490 Centurions were produced in 1970-71, and that was it for the
production of the mean little greenie. Was this some freak bike that Kawasaki dropped on the public, only to
pull it off the market in two short years? I remember the distinctive noise the bike made with the open stinger,
and steel rotary valve, as nothing else sounded like it. Many a 250 rider was embarrassed when a little
100cc green bike roosted them through a corner, and disappeared down the straight.  
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