Classic Machine
Yamaha TY 250cc
The early seventies witnessed an incredible interest in one-day trials and off-road riding in general. Not just in Europe but also around the globe in Australia, America, Canada and Japan. This gave Ossa works rider Mick Andrews and his wife Jill the chance to tour America, where they made many friends. The 1973 International Six Days Trial was due to run in America so Mick and Ossa went over in 1972 to practise and also set out on a promotional tour to help create some much needed sales for Ossa machines. At the time Ossa were going through a rough patch due to many financial problems. Whilst practising with American ‘Ossa Yankee’ rider Barry Higgins Mick had a serious crash and badly separated his shoulder. The prognosis, after two operations, meant no serious motorcycling for a six-month period. It was during this period of recuperation that Yamaha first made contact with Mick – in really bizarre circumstances. He was eating in a restaurant at Los Angeles airport when a tannoy announcement was made for Mick to go to a reception desk to take a telephone call. He took the phone call, and it was from Yamaha road-racer turned team manager Rod Gould. This was the start of a new chapter in the life of Mick Andrews. Words: John Hulme Pictures: Eric Kitchen, Yamaha, Doug Jackson, Morton’s Archive and Yoomee Archive
Gould was well aware of Andrews’ development capabilities, having witnessed his work first hand with the Ossa project. Yamaha wanted the top riders on their machines and Gould’s job was to hire Andrews. He asked if he would be interested in developing a trials machine for Yamaha in Japan. You must remember, around that time Sammy Miller had moved from Bultaco to Honda, Don Smith from his privately owner Montesa powered ‘Stag’ to Kawasaki and Gordon Farley from Montesa to Suzuki. The tide had turned on the Spanish trials machines and was now heading to the Land of the Rising Sun, Japan.
On his return home and after giving the idea a great deal of thought Mick decided to return their call with an answer. A deal was struck and he became the Japanese factory’s first works trials rider. The new 250cc production machine was nearly ready in Japan but they waited for Andrews to make his suggestions on how to improve the machine. He suggested some changes to the motor and the chassis, using his knowledge and experience to finetune the new production model.
After many hours spent in Japan his new ‘works’ machine arrived in February 1973, along with a Japanese engineer to help Andrews develop his ideas which were to be incorporated into the production machine. They spent many hours at his home practice area at Burrycliff Elton, in Derbyshire, on the machine but it still needed much work.
It was rumoured to have an engine size of 360cc. Mick gave the machine a tough baptism though — in the opening round of the European championship held just outside Barcelona, near the home of Ossa — and the Spanish fans were not happy! Andrews had a tough time with the crowd but still came home in seventh position.
Not one to be intimidated though he took sweet revenge two weeks later when he won the French round of the European championship.
His next target would be the Scottish Six Days Trial, an event he had taken a hat-trick of wins in from 1970–1972. Could he become the first rider in the long history of the event to take four wins in a row?
During the six days of the event based around Fort William he was up and down the leader board. He finished day two in third position, day three in sixth position then moved into the lead on day four before slipping to second, where he eventually finished, just behind the winner Malcolm Rathmell. Andrews had been unlucky not to win but had proved to Yamaha the potential of the new machine.
It was the same story in the European championship where he was aiming for an unprecedented hat-trick. He finished runner- up but he had used the championship to help develop the works machine.
Andrews had a few small, insignificant, disagreements with his development team concerning the production machine, when the computer did not agree with his ideas, but it was so close to being ready to be released to the public. Happy with developments the Yamaha team in Japan pressed the button and the assembly-line wheels began to turn out the TY 250cc in summer 1973.
Production
The official introduction of the new model was on the 3rd August. It looked superb with its silver frame and yellow-and-white colour scheme. The engine had been thoroughly designed and constructed for very low-speed performance. The ‘Torque Induction’ engine was ideal for this low-speed operation since its primary characteristic was to develop more torque over the lower and middle speed ranges. The reed valve and seven port cylinder design would aid scavenging efficiency and therefore improve the important throttle response, giving the rider a more positive feeling of the machine’s performance. The piston used an ‘L-Type Keystone Ring’ as it yields a better sealing characteristic.
When the trials machine is operated hard at low speeds the engine will become rather hot causing expansion to occur, thereby reducing compression; this Keystone-type piston offers a better application for the trials motor.
The crank and flywheel magneto system were also different from those currently found on the trials machines, in that a large rotating mass was required or the motor would stall at low speeds; however the mass must also be light enough to offer a rapid throttle response time. With these requirements as a guide the optimum weight and design for the crank and flywheel were selected.
The gear box was a five-speed unit with the first three gears aimed at trials use and the other two for higher speeds when travelling around the course.
And the icing on the cake was the fact that, over its Spanish rival machines, the Yamaha could be started with the machine still engaged in gear.
Another first on a trials machine was the use of an ‘Autolube’ system, using a separate oil tank from the fuel which mixed the two together meaning the rider did not have to pre-mix the fuel before putting it in the tank.
The quality of the other components was excellent and enhanced the machine’s trials looks. The wheel hubs were far superior to the Spanish machines and they had a unique sealing system for the brake chamber to help keep the brake shoes dry.
Many components were made from aluminium and magnesium to help reduce the overall weight.
The front forks provided excellent suspension, providing a long cushion-stroke, which also gave extra rigidity and in turn ensured a more efficient and lasting damper action. It was the same at the rear as the chrome-finished shock absorbers were multi adjustable.
Also incorporated in the rear swinging arm was a chain oiler to keep the chain lubricated at all times and a rear-facing chain tensioner. The new machine had lived up to all expectations, and all they had to do now was sell them.
The engines design was purely for trials and included Torque Induction – Autolube – Keystone ‘L’ type piston ring Mick and Jill Andrews had a fantastic time promoting the new machine around
the globe
Mick and Jill Andrews even featured in the promotional brochures for Yamaha
Cantilever Shocker
As soon as the season was over Andrews went straight to Japan to discuss developments of his 1974 works machine before travelling to Australia on a promotional tour to promote the new Yamaha TY 250cc.
Mick and Jill had a fantastic time, as the motorcycling public loved to see Mick perform on the new Japanese machine. Yamaha also used this time to make many promotional and marketing films and brochures featuring their new machine.
During the latter part of the trials season in 1973 Andrews had started to use a 250cc cylinder on his machine after initially testing with the 360cc. Yamaha were promising something special in the way of a new 250cc for the 1974 season but when it arrived in the UK it blew even the usually calm Andrews away!
It was February and the weather was cold but this new Yamaha was the hottest property on the trials scene in generations.
The Yamaha Motocross team had successfully introduced the ‘Cantilever’ singleshock frame in 1973, designed by Belgian engineer Lucien Tilkins, and it was also successfully adapted for the road racing team, so why not trials? The new machine was radical to say the least, on looks alone. With no rear shock absorbers visible the whole of the rear sub frame pivoted from
its lowest point, and the rear wheel was carried at a separate apex before a third contact point connected with the single large-capacity gas filled shock absorber. This single unit ran up under the fuel tank to a location point behind the steering headstock. This idea was supposed to allow for more rear wheel travel and also adapt better to weight transfer situations by the rider.
Various other components on the machine were new but even more was to come. At first the machine used a conventional carburettor but, less than a month later, this was swopped to a form of fuel injection. This was a conventional looking Mikuni branded carburettor but the float bowl was replaced by what looked like a block of rubber. It was in fact the ‘brains’ of the new concept of fuel injection which had a tube connecting it to the crankcases, which in turn pumped fuel using the pressure generated to control the fuel supply. Andrews loved the machine and it also demonstrated Yamaha’s commitment to its future in trials.
SSDT Winner
Mick was full of enthusiasm for the new machine and when he won the 1974 Scottish Six Days Trial on it he gave Yamaha the privilege of having the first ever win by a Japanese machine in this prestigious event. He would also give a Japanese motorcycle manufacturer its first win in the world trials championship when he won the Belgian round on his way to third overall in the series.
Back in Japan they were getting ready to make changes to the production machine for its launch in 1975, having learnt so much from the development work carried out by Andrews and his team with the works machine.
They moved back to twin rear shock absorbers and a conventional swinging arm for another win for Mick Andrews at the SSDT in 1975, having learnt all they needed to know from the ‘Cantilever’ machine. The red-andwhite fuel tank carried on the works machine was carried over to the new production machine in 1975.
Other changes were made to engine internals and new, narrower, clutch and magneto cases were fitted. A new cylinder barrel appeared and the seat’s design was also changed.
The new machines looked good but the buying public did not take to them. They were more expensive than the Spanish machines from Bultaco, Montesa and Ossa. They also wanted a machine that performed the same as the one Mick Andrews competed on and did not see the attraction of the production TY 250cc, which they considered inferior to the one Andrews had. The production machines were sold worldwide with only minor cosmetic changes such as the fuel tank colours and transfer designs.
At the end of 1975 the development programme was over, having run its three year term with Andrews, and Yamaha Japan pulled the plug on the development programme in Japan.
Mick signed to ride for the Dutch Yamaha importers and moved to Holland, where he continued for a period of time still riding variants of the Yamaha trials machine in all the major trials competitions.
In 1978 production of the Yamaha TY 250cc was over even though machines would still be sold right up until 1981, but as this era came to an end a new one started with further private development of the machines, and we would see Yamaha powered Majesty and Whitehawk machines using the TY 250cc engine.
Mick Andrews became involved with long-time friend John Shirt, and the Majesty project was born putting him back on a Japanese engined machine.
The initials Mick Andrews John Edward Shirt Trials Yamaha was the title given to the new Yamaha converted trials machine that John and Mick developed, with the 320cc version of the machine winning the 1980 British World Championship round.