Cheney Yamaha 250
CHENEY YAMAHA 250
CYCLE WORLD IMPRESSION
An Ultra-Lightweight Chassis Conversion For The Popular DT1
IN THE 1950s, ex-works rider Eric Cheney began modifying and making specialized components for motocross machines in a shop the size of a one-car garage. Today, in an area only four times as large, Cheney is producing one of the lightest and best handling chassis kits available.
Unlike some manufacturers. Cheney does not build one "universal" kit to tit "most" engines. Rather, he builds his kits for use with specific powerplants to insure proper handling.
As with the other models, the Yamaha version is available in two stages, a complete chassis and a basic frame kit. Our test machine was constructed from the chassis kit. which is. in every aspect, a complete motorcycle, less engine and electrical components.
The basic frame kit. on the other hand, is designed for the person who already owns a 250 Yamaha, but desires a "professional” handling mount. The kit contains the following: the frame and swinging arm assembly; folding foot pegs; a brake pedal that will work on either the right or left side; a 1.5-gal. gas tank; aluminum fenders, aircleaner box and side panels; an expansion chamber; modified Koni shock absorbers; and the necessary bushings and spacers to adopt the stock Yamaha rear wheel and fork assembly.
Cheney builds his nickel-plated, single backbone, double-cradle frames from Reynolds 531 tubing. An aircleaner box, containing a polyurethane foam element, shares the space under the seat with the expansion chamber, which exits on the left side just beyond the upper shock mount. The upper shock mounting bolts serve as mounting points for the aluminum side panels.
The forks, offering 6.75 in. of travel, are of Cheney’s own design and weigh only 17 lb. Weight reduction is further aided by the use of Elektron hubs and alloy rims. Dry weight is 198 lb.
Of interest is Cheney's method of rear axle adjustment. Eccentric plates, located at the rear axle, are rotated until proper chain tension is achieved. The rear wheel's position is maintained by a locking key which fits into the adjusting plates’ slotted outer edge. As long as the corresponding slot is engaged by the locking key on each side, the rear wheel will be in alignment with the swinging arm assembly.
The Cheney Yamaha loaned to us for testing took a little getting used to. Bill Oury campaigns the machine in motocross events across the country and has considerably modified the DTI engine. Plenty of power is available, but the unit must be kept high up in the rpm range. Aided by a five-speed, close-ratio gearbox, however, the Cheney Yamaha gets it on.
The rough terrain encountered in motocross makes a standing position almost mandatory, and the handlebarfootpeg relationship is just right for this. The seat and narrow gas tank do not interfere in any way.
Handling, due to the light weight, can best be described as super responsive. Dampening, both front and rear, is excellent, and the Cheney has no tendency to over-loft the front wheel, unless the rider desires it. Braking, however, is almost too severe.
Cheney Yamahas are currently available from Cheney Imports Ltd.. 24 El Sereno Drive, Colorado Springs. Colo. Frame kits retail for $598. The chassis kit sells for $995.
