Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/125980
00 ....-i The Cooper 250 in t he real world of rough t rack competition. Update: Bringing the Cooper 250MX into 1975 By John Huetter Considering the stability of the peso in the world money market and the discovery of oil on the coast of Campeche, someday all motorcycles will be built in Mexico. The Cooper 250 MX, th e resu It 0 f an am algam 0 f German, American and Mexi can design re- 24 quirements, already is. Just recently, a major retrofit effort has been mounted bring this North American to motocrosser up to the competition technology standards of 1975. The effort still isn't complete and this is not so much test as progress report on the state of one of the last affordable dirt racers with good handling. The basics haven't really changed, which is both bad news and good news. The Moto Islo engine is heavy, but produces plenty of competition-level horsepower, some of which is choked off by a mediocre expansion chamber design that doesn't silence too well, either. The motor will stilI p ull with other 250s in its racing class at peak power but could be a whole lot better, and quieter, with a different pipe. It wants to be revved to work effectively and tends to make its power like a good 125. It just makes a lot more power. Few people ever complain about a 250 Cooper being too slow. The frame is avirtual copy of a Maico frame of 1972-73 vintage. As su ch, it slides outrageously well (which accounts for some of its oval track success with the appropriate tires) and, in general, com ers quite . adequately. One im provem en t over its heredity is that the Cooper frame doesn 't seem to crack like 1972 Maico frames had a ten den cy to do. The chassis is strong and flex-free. There are two su bstantial imp rovem en ts in the current Coopers which, while not making it a new model, make the existing package a whole bunch easier to ra ce. Th e footpegs have been lowered wh ich results in a much better body relationship to the bike and ge ts the rider's knees down below the gas tank. Also, the brakes now work. New brake shoes are the main reason an d litde or no fade could be detected in the throttle on-brakes on-throttle on routine of motocross cornering. They are finally up to the job. . The knobbies are of a new (for Cooper) 'tread design from Bridgestone which replace the previous chevr on pattern and will do the job very nicely till they require normal replacement with rubber of your choice. That might be another Bridgestone, especially on the rear. They're really not too bad . The fenders, such as they are, have . not been changed. Both fiberglass units are too short, allo wing a stripe of muddy spray up both your bac k and front, and they cra ck too easily. Also, the rear fender interferes with rear Our rider (top ) approaches the updated Cooper w ith some caut ion. Bolt -up shock mod works bette r t han it looks. Same goes fo r the re-pattern ed Bridgestone (abo ve) . wheel travel in the new LTR suspension configuration now availab le which is really what this report is all about. Both co uld, and should, be replaced with plastic mudguards. TI,e cost is about $11. The previous suspension consisted of seven inch travel Bctors made under li cense in Mex ico and similarly-produced Boge dampers (black-bodied type) with 2.5" effective piston travel and 60-90 lb.jin. progressive springs. Cooper has just introduced some bolt-on shock mounting brackets that move the lower shock position about four inches forward on the swingarm and allow nearly five inches of rear wheel travel, with the noted result that the rear wheel graunches the fiberglass fender. After a couple of days of riding, we came to the following set of conclusions about the bolt-on LTR suspension mod. One, the idea actually works. Two, the increased rear wheel travel with resultant weight and force transfers were too much for the stock fork springs. They soon give up and sag leaving about 5.5" of uncertain-feeling mushy fork travel. This effect will be noted in just about every LTR modification. Three, the 60-90 progressive springs on the Boges weren't the hot set-up after nearly doubling the rear axle travel. Solutions were incredibly simple considering the positive results. Basically, the bolt-on brackets do the job and the Cooper swingarm proved rigid enough and strong enough not to bend or deflect under pounding. New S&W fork springs of a sturdier wind were crammed into the fork tubes and brought back nearly seven inches of honest, firm fork travel while taking