By 1973, the Japanese manufacturers realized that warmed-over trail bikes wouldn’t cut it in the growing American motocross market. Though Kawasaki had been one of the first to introduce a 250cc class motocrosser—the 1968 F21M 238cc Scrambler—that machine was best suited to smooth scrambles tracks. Kawasaki followed in 1970 with the Big Horn 350 Scrambler, a rotary-valve machine that would prove to be a “dust collector” in the dealer showrooms.

Motocross was popular in America, and Kawasaki wanted to capitalize on the growing trend, so they hired Swede Olle Pettersson to develop the bikes and Brad Lackey to compete in the AMA 500cc National Championships aboard a factory works bike. Brad rewarded them with the 1972 500cc National Championship.

In preparation for the 1973 season, the factory built a limited-production run of 200 units, dubbed the F11M 250. Bryon Farnsworth, Kawasaki’s R&D manager at the time, says, “We used Peter Lamppu and Jim Cook as test riders and Kawasaki Japan contracted Thorlief Hansen to race it. Our riders were impressed with the power; the finish was good, but the suspension and handling still left something to be desired. The Japanese focused on the 250s as their test riders were smaller, and we focused on developing the 450, which was called the F-12MX 450. Heck, the Japanese test riders couldn’t even start the 450. We had to do it for them!”

By 1974, Kawasaki introduced the KX nomenclature to identify its line of motocross bikes and later hired Gary Semics and Jimmy Weinert to pilot the factory machines. Weinert rewarded Kawasaki with a 500cc National title in 1975 and a 250cc Supercross title in 1976.

Nobody seems to know what the retail price was for the 1973 F11M 250 because they were sold in such limited numbers, but the 1974 KX250 retailed for $1150. The two-stroke, piston-port engine’s bore and stroke was square at 68mm x 68mm. It was fed by a 32mm Mikuni carburetor. Claimed horsepower was 29.5 at 7500 rpm. It had a five-speed gearbox, multi-plate wet clutch and magneto ignition system. The lime green plastic gas tank held 1.85 gallons of gas. The footpegs folded up but were not spring-loaded. Shoulder-less DID alloy rims carried Japanese-made Dunlop tires (4.00/18 inches at the rear and 3.00/21 inches up front). Brake drums were 130mm and 150mm front and rear respectively. Weight was a Kawasaki specialty, as the 1973 Yamaha DT3 MX weighed 238 pounds, the Suzuki TM250 220 pounds and the Honda CR250M 228 pounds, while the Kawasaki was a feathery 206 pounds. The 1973 F11M had a very unique, stamped down-pipe with a built-in silencer. The plastic parts are impossible to find; the green gas tank, black plastic airbox, black rear fender and black front fender with the Kawasaki “K” molded in are rare. 

Our Early Years of Motocross Museum’s 1973 Kawasaki F11M was bought unrestored for $6500, but needed $5000 worth of work to get it back into pristine condition. The F11M is rare, as less than 200 of them were made, but these bikes are not highly regarded by motorcycle collectors.


1968 F21M 238cc Scrambler1973 kawasaki F11M 2501979 Big Horn 350 Scramblerbrad lackeyBryon FarnsworthCLASSIC MOTOCROSS IRONclassicironKAWASAKImotocrossmxaolle petterssonThorlief Hansentom white