1979 Z650-B3
The only difference over the B2 model was a change of graphics. Sales once again picked up. The new lower case tank badges were also used. The frame covers were revised to eliminate the recessed badges so that the outer surface of the cover was now totally flat.
One mechanical change on this and subsequent models was the introduction of an "automatic" cam chain tensioner and associated bits. Until this time, the cam chain tensioner had been a manual type requiring attention from the owner on a regular basis. The automatic tensioner, however, was a dismal failure and was eventually changed out for the Mark II version (automatic cross wedge type) on the 1981 models. The Mark II design was somewhat better but still not a proper solution.
As well, the US-only models got the air injection system for emissions reduction. These variants are immediately recognizable by the two reed-valve housings and associated plumbing on top of the valve cover on the forward (exhaust) side of the engine. There is also an air diverter valve assembly (with associated hoses) bolted to the main frame tube just under the gas tank. The US-only models kept this same setup through to the end of production with the 1983 model year.
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