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• Auction House:
  Donington Auctions
• Sale Name:
  Collectors' Motorcycles, Cars & Horse Drawn Carriages - Featuring the Private Museum of Racing Driver Bryan Thomson
• Sale Date:
  20 Jun 2021 ~ 2pm (AEST)
• Lot #:
  17
• Lot Description:
  1974 YAMAHA TZ750A
  One of the most important road racing motorcycles of the 1970s
• Notes:
  When Suzuki and Kawasaki introduced their immensely fast three-cylinder two-strokes and adapted them for the US AMA and FIM Formula 750 racing in 1972, Yamaha knew they needed a counterattack. AMA rules stipulated that 200 production units were required for homologation but by that stage Yamaha was committed to the development of four-stroke larger capacity machines. Although the regulations implied that production road bikes should be the basis for homologation, this wasnt specifically stipulated, and Yamaha managed to persuade the FIM to allow the homologation of 200 750 four-cylinder two-strokes for 1974. Yamahas new F750 contender drew on their successful two-stroke TZ350 and YZR500, and although few components were shared the engine was basically a doubled up TZ350. The TZ350s 64x54mm bore and stroke provided the first TZ750A a capacity of 694cc. Instead of the TZ350s piston port induction the TZ750 shared reed valve induction with the contemporary YZR500 Grand Prix machine. Reed valves were introduced to flatten and broaden the power delivery of the already detuned water-cooled engine. While potentially capable of 140 horsepower, Yamaha chose to restrict the power of the early examples to 90 horsepower at 10,000 rpm. A steel, twin-shock frame reminiscent of the Rob North-designed unit used on the racing BSA/Triumph triples housed the new engine. The pre-production TZ750 prototype was tested in Japan in 1973 by Australian World Champion Kel Carruthers and by the end of the year production examples were being delivered. John Boote provided the TZ750 its first international race victory in New Zealand in January 1974, but the Daytona 200 in March was where the TZ750 made its biggest impact. With fifty TZ750s entered, victory went to Yamahas new recruit Giacomo Agostini, with Kenny Roberts second, slowed by a cracked exhaust. TZ750s filled all the places from twelfth to thirty-second. This success saw the TZ750 banned by the FIM for the rest of 1974. But with the ban lifted in 1975, until 1982 TZ750s were almost unbeatable in Formula 750 racing and the TZ750 won the Daytona 200 nine consecutive times from 1974. Privateers the world over were able to compete against the factory teams in Formula 750, packed grids of near-identical bikes making for close racing. Those who witnessed these demanding machines being wrestled around Bathurst, UK short circuits, the Isle of Man TT or Daytonas bumpy banking will never forget it. Only around 600 TZ750s of all types were built between 1974 and 1979, with approximately 219 of the first TZ750A. Today these rare spectacular machines are highly sought after by both collectors and classic racers. The engine in this bike was one of a batch made by Yamaha in the 1980's for side car racing and has factory sand cast crank cases with no serial number. It was bought by former Kawasaki UK factory rider and later sidecar racer in Australia, Barry Ditchburn from Terry Goldie in the mid-1990s. This engine was stripped, and the cases were crack tested and repaired as required by an aviation approved welding service at Moorabbin airport. There were no major issues with the cases and Barry rebuilt the engine with RD LC 350 cylinders and fitted it into a RZ 250 frame, with the view to road registering it. Dave Jackson rode it a few times but wanted to build a true TZ750 so began looking for a frame. The reassembled engine was kept as a spare. In May 2007 Dave bought a Triumph triple-engined TZ750A framed bike from Garry Smethurst in Sydney. Although street registered this bike retained most of the genuine Yamaha TZ750A chassis components, including front fork, wheels and brakes. The Triumph engine was removed and sold, and Barry looked at installing the TZ engine back into the bike. Unfortunately, the frame had been extensively modified and whilst looking for one to copy a TZ 750A (#156) frame was listed for sale on eBay from Tony Skinner, via Norm Randall in Sydney. bought the frame on Barrys advice for $3300 in December 2009. This frame apparently came from Newcastle, possibly from Allan Kay and could have been ridden by Gary Coleman. Barry and David then began collecting parts. They already had a good 347cc 40900 cylinder and NOS pistons and rings, plus one correct expansion chamber from George Huse when Milledge Yamaha closed. The other three pipes came from Mal Pitman in South Australia. It has Koni rear shocks, but comes with the originals, one complete and one disassembled with the spring adjuster and retainer missing. The magnesium front hub is included but was changed to an alloy XS 650 unit when the bike was street registered. The water temp gauge is also not original. Following four years of work and searching for NOS, used, and some reproduction parts, the bike was finished. After testing at a private airstrip in Victoria it was put into dry storage until Barry Ditchburn had it recently recommissioned and dyno tested at 92 horsepower. It is being sold to fund a Period 5 TZ750 racer. In exceptional original condition, this 1974 TZ750A is offered with all receipts and a video of it running on the dyno. This a very rare example of one of the most legendary racing motorcycles of the 1970s; the Yamaha TZ750A.
• Estimate:
  A$55,000 - 65,000
• Realised Price:
  $0.00
• Category:
  Automobiles & Accessories

This Sale has been held and this item is no longer available. Details are provided for information purposes only.