Additional photos of this Cooper 250 MX are available here for your perusal.
The Cooper motorcycle company was born in Burbank, California in 1972 by Frank Cooper, who was the American distributor for Maico motorcycles. Off-road motorcycling experienced a boom in popularity and Cooper sought to fill a void in the motorcycle marketplace between the less expensive, entry level Japanese motorcycles and the more expensive European motorcycles.
Cooper contracted with Isidro Lopez, the owner of a Mexican moped manufacturer named Moto Islo, to build motocross and enduro motorcycles to his specifications. He initially utilized engine parts made in Italy and later bought engines made by Sachs, importing the motorcycles into the United States as Cooper motorcycles beginning in early 1973. Cooper produced an MX 250 cc model designed by Malcolm Smith using an engine based on a Yamaha two-stroke engine.
The Cooper 250 Enduro certainly stood out, with a bright lemon yellow fiberglass gas tank, fenders and triangular side-panels.
Steel rims held the Bridgestone knobby tires in place, with a 3.00 x 21 on the front and a 4.00 x 18 on the back. The frame was a full cradle with double down-tubes, made of lightweight 4130 chromoly tubing. Though the engine had a rather Yamaha-ish look about it, Moto Islo was using its own reinforced 200cc crankcase, albeit with a DT-style top end. Everything from the connecting rod on up could be sourced from a Yamaha parts book if needed. It had the same 70mm bore and 64mm stroke of the 246cc DT – imitation is the sincerest form of flattery.
Ground clearance was a reasonable 10 inches, with the seat at a tad over 31 inches. A reasonably comfy extended saddle kept the rider’s butt from protesting too much. A Nippon Seiko speedo went to 100 mph. Dry weight was a claimed 227 pounds, with a wheelbase of 55 inches.
The first production bikes began appearing in U.S. shops in the spring of ’73, and riders were impressed with the power and the good handling. The engine, depending on tuning, was rated at anywhere between 23 and 28 horsepower. The factory had instructions for the serious contenders who wanted to increase performance, like reducing port timing on the piston-port engine, or bolting on a 34mm carb.
This Cooper went through a restoration, however details of the work are unknown. It presents impeccably, and has not been ridden since the restoration.