In June 1967, "Cycle World" published this unique feature about the very first Yamaha 350 cc racer.
The Yamaha Z608, as it was called, was a prototype, built by Japanese engineers and Yamaha US staff to participate in the Daytona 200 miler. Two machines were built and ridden by Mike Duff and Tony Murphy. Mike qualified 8th fastest amongst all the big bikes and had it not been for a broken gastank, could have placed very high. 4 Machines more were built later for the Daytonaraces. Cycle World called the bike "TR-1", but it was very different from the European TR1 some 20 years later!
"Cycle World" tested Tony Murphy's bike and said that it was "probably the best, most difficult to ride, racing machine, ever devised by man"
You can see that this machine,in contrary to the YZ608, still has standard YR1 frontforks with the shrouds still on. Also the carburetors are the TD1B type with separate floatchambers (Amal 276 type 30 mm Mikuni's) Even the kickstartershaft is not removed.
The engine is fitted into a genuine RD56 chassis (as per AMA rules) and the seat and tank are used as well from the same machine. Cylinders had chrome bores (as the TD1's). As the AMA rules permitted only 4 gears (because of the ancient Harleys of course.....!), the first gear was blocked off and a new topgear was designed. Topgearing was 142 mph at 9.500 rpm (227 km/h). The 2 machines ran with the standard Yamaha Autolube lubrication.
These were also the first bikes with (experimental) electronic ignition. Performance was given as 45 hp
These old pictures give a good idea that Yamaha tried very hard already with this machine to have a "weapon" for Daytona. It was just a few years before Don Emde clinched the first from many Victories for Yamaha on that famous circuit!
And finally I got the official Yamaha picture of the Prototype TR1 just in front of the Yamaha Workshops in Japan. Just in time ready for Daytona. Here you can also see that the story in "Cycle World" was not correct. The machine was built in Japan, maybe upon request from Yamaha US, and after shipment to YMUS it was "readied" there for the race.
You can "click" for a nice large picture. Clearly you can see the standard YR1 front fork with the forkshrouds still attached!