Some Yamaha MX250/360 history

NQ1965

PR Elite
Interesting read on the MX250 and 360's.
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http://www.cyclechaos.com/wiki/Yamaha_MX250


The Yamaha MX250 is a motorcycle produced by Yamaha from 1973 to 1975.

The year 1972 was a good one for Yamaha, which, in its second season of works participation in motocross Grand Prix, finished second in the 250cc class with Hakan Andersson and fifth in the 500 class with Van Velthoven, while the YZ250 of Gary Jones won the AMA championship.

Redesigned Frames
Yamaha's great strength is its speed of reaction. The 1973 MX privateer's machine was a genuine replica of the 1972 works machines. The cycle part was completely redesigned, with the engine set lower in a new double cradle frame, while the rear shockers introduced a separate hydraulic fluid tank with external adjustment of the damping. This marked the beginning of a trend towards ever greater sophistication of suspension systems. It was underlined at Yamaha by the introduction of cantilever rear suspension in 1973.

World Champion
The major revolution in two-stroke engine design, which was to bring automatic intake valves -first on the cylinder, then in the crankcase -and valves in the exhaust, still lay in the future, so the MX250/MX360 Yamahas of 1973 were somewhat lacking in flexibility. Yamaha was world 250cc motocross champion in 1973 with Hakan Andersson, while bikes entered by the French importer Sonauto won the national 125cc championship with Jallat riding and came second in the 500cc class, this time with Drobecq in the saddle.
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40 Years Ago
Yamaha Launched the MX
http://www.motocross.com/uncategorized/40-years-ago-2/
 
Yaller. http://vintagemx.com.au/1974-yamaha-mx360-bike-test Lots of good stuff on this site.

The huge Skyway silencer on the big bore '74 Yamahas was different. Looked more aftermarket (afterthought?) than stock with a rubber, center attached flapper valve thing on the end. The smaller Yamahas of that time came with a nice, small welded on silencer. Those welds had a tendency to break but: they were much cooler than that Skyway contraption.
 
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