By Troy Johnson
“Was that a six?” “It looked like a CBX engine?” “That was no CBX.” “What was that?”
Bewildered comments like these follow Greg Smith whenever he rides his bike into town from his farm in Elk River. If you’ve seen this six-cylinder, pearl-white puzzle roll by on a sunny, Sunday morning, you have had the privilege of gazing at a Moto Martin framed CBX. This is one of the two currently garaged in the United States.
The six-cylinder, 24-valve, CBX powerplant is a large landmark on the road of Honda engineering, and the bike has become one of the few Japanese collectibles. Surprisingly, this beloved machine was a thorn in Honda’s side during its production life.
The bike didn’t sell. It didn’t sell in 1979 and 1980 as a twin-shock, unfaired standard, so Honda added bodywork and a mono-shock in 1981 and pointed the CBX to the touring market. It still didn’t sell. After the 1982 model year, Honda was out of ideas for its six, and Honda warehouses were full of unsold CBXs. They pulled the plug.
Honda inadvertently insured the CBX’s future cult status by giving the leftover bikes to mechanics’ schools. The 100+ horsepower, 1,047cc six imprinted itself into the brains of scores of young wrench-spinners, and the schools’ CBXs were unregisterable–brand new parts bikes.
One of the reasons for the CBX’s dismal sales was its handling characteristics. It weighed in excess of 580 pounds with fuel and sported a frame that, if ridden hard, allowed the engine and wheels to go in three directions at once.
The French firm, Moto Martin, was not as quick as Honda to give up on the CBX. In 1984, Moto Martin isolated the handling problems and eliminated them by unbolting the engine and throwing everything else away. Right motor, wrong bike.
Moto Martin provided the big six with a new home that was both stiffer and lighter than the original. They used the original CBX chassis geometry (58.5″ wheelbase, 27.5º rake, 4.7″ trail) as a jumping off point, but they tied the front and back of the bike together with a straighter, saner frame. The polished nickel tubes came off the steering head, made a wide bow around the bank of six stock carbs and turned once a couple inches above the swing-arm pivot to clear the lower crankcase. 42mm Moto Martin forks replaced the stock 37mm tubes. The mounts for the single, rear shock place it horizontally under the seat. The fiberglass seat/tank/tail section was one piece. Brembo supplied the brakes, and the whole works weighed just over 500 pounds with fuel.
The engine in Greg Smith’s example is an ’81 crate motor, that he found in California and just finished breaking in. This bike is fitted with Dyna coils and ignition and Stage 3 jets.
The frame rails don’t leave much room for air cleaners, so Uni filters work best. The exhaust system is a beautiful D&G six-into-one unit that Greg sent out to Airborne for a ceramic-on-steel coating. This has given the pipes a deep, semi-gloss luster and left them impervious to corrosion. The handle bar is a solid aluminum piece from K&M.
Moto Martin supplied this chassis in kit form, so each motorcycle is slightly different in the details. Smith is the proprietor of Kuhnhenn Machine Werks and fashioned the billet aluminum parts on this Martin specimen himself. His creations include the triple clamps, the motor mounts, the footpegs, and the aluminum fork boots that replaced the pedestrian rubber boots. There is no chrome on this motorcycle. All the shiny parts are polished metal.
Both Greg Smith and a 1984 issue of Cycle News praise the Moto Martin’s road manners. Smith says his bike is “always stable.” Cycle News shaved four seconds off the previous best CBX lap time at Willow Springs while taking care not to scrape anything on their bright red Martin loaner.
The Moto Martin CBX is an uncompromised cafe racer. It has a legendary engine, a chassis that keeps everything moving in a straight line, and the simple elegance that defines the genre.