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The Air Cooled Models - TD and TR.

YDS1R    It was 1959 / 1960 when the very first production Yamaha roadracer hit Yamaha dealers in selected countries, including Australia,  in the form of the YDS1R. They were sold both as a complete race bike and as a kit to convert a YDS1 road bike into a racing machine .
At the moment there are no figures at hand for the rest of the world, but here in Australia approx. 10 were sold, making the YDSR1 a very rare machine indeed. Just five of the ten are known to be still in existence.

Picture: Nihal de Silva at speed on the first Yamaha to be imported into Sri Lanka (formerly Ceylon), a kitted YDS3 racer, in the early seventies.

There was also a race kit sold for the next model 2 stroke 250cc roadbike from Yamaha, the YDS2, which comprised of  basically cylinders, heads, pipes , carburettors and magneto. The kits were available around 1962 prior to the release of the TD1.

Picture: TD1 courtesy of Mitsuo in Japan

TD1    Late in 1962, following the successes of Fumio Itoh, Larry Beale and others over the preceding 10 years of racing development, Yamaha released their first  production roadracer, the essentially YDS-2 based TD1. The new bike was relatively easy to put into production since a lot of the components, such as the 27 litre tank, brakes (twin leading shoe drum on the front fitted with a cooling air scoop, single leading shoe on the rear), seat and other running gear were taken from  the old RD-48 factory 250cc racer of the previous year, in that the  jigs and plans already existed.

It had a very similar frame layout to the YDS-2 but was made from lighter material, and had completely different front and rear suspension. The entire front end from top triple clamp to axle was a race special assembly including fork legs, fork tubes, triple clamps, handle bars etc. The swingarm was what appeared to be an approximate copy of the RD-48 unit and was made from a lighter steel than the YDS-2 unit and the rear shocks were entirely different also.

27mm pot-metal carbs, an MC-2RY magneto ignition and 5 speed wide ratio gearbox adorned the machine, along with a cylinder wall lining consisting of anodization of the aluminium cylinder itself. To minimize the risk of seizure the factory had worked out years earlier that it was essential to match the metallurgy of the piston and cylinder so that the required piston/cylinder clearance wasn’t reduced as the motor temperature rose. Very high silicon content was necessary for the pistons and new technology used during casting to control the way the piston behaved as it was made. Legend has it that a handful of customer TD1's came with chrome bores though this is unconfirmed.

Picture: The TD1 pictured with the fuel tank missing was the first Yamaha to win in the UK & Europe, winning the international
level "Norwich trophy" in May 1963. Bill Ivy also rode it. ( thanks Richard Tracy for the info. )

The clutch was mounted on the end of the crankshaft and was renowned for slippage and usually good for just one fast start anyway. At times the end of the crankshaft, being just 20mm in diameter, holding the clutch would snap right off, with the clutch busting out through the sidecase in a frightening manner !! First gear was very low, which helped with starts, but the huge gap to second meant that first gear was so low it was useless out on the track once the race was underway. This unusual gearing arrangement, combined with very stiff suspension, under-damped forks and "time bomb" clutch made the bikes difficult to ride, though they won races nonetheless.

Legend has it that around 60 TD1's were produced, with the vast majority of these going to Australia and the USA. They came from the factory fitted with lights and turn signals, covered the 1/4 mile in 15 seconds, and cost around £500.

A 255cc version of the TD1, named the TE1 was released at the same time which was essentially the same bike with a 1mm bigger bore.

Picture: The first TD1A imported into Australia ( John Rettig )

TD1A    The TD1A was released in 1963. There were a lot more differences between this bike and it's predecessor than most people realise, some of which were:  They differ in regards to the frame, forks, triple clamps, steering damper assembly, tacho/fairing bracket, front and rear fenders, expansion chambers, seat, as well as some other minor parts vary from bike to bike. As well, 2nd, 4th and 5th gear ratios were changed. Yamaha manufactured 60 or so of these as well.

TD1B    The 1965 season saw the introduction of the new TD1-B. Yamaha had decided to do away with the sometimes unreliable anodized cylinder, with a porous chrome plating applied to the aluminium cylinders designed to retain oil and assist with engine durability. The entries into the transfers were able to be enlarged thanks to the cylinder bolts being spaced further apart, though their port areas remained the same as the previous model.

( Picture courtesy Mitsuo in Japan )

Exhaust timing was advanced by simply notching the pistons by approximately 2mm, inlet timing was altered by machining 9mm from the rear of the pistons as well. The big and small end bearings were updated also. New exhausts also made an appearance and this, combined with the piston  mod,  pushed the peak revs up 500 to 10,000rpm.

A new, sleeker looking white fuel tank graced the TD1B and the exhausts were now painted black and mounted to the frame using spring loaded brackets, along with this the remote carby bowls were mounted on a special bracket secured directly to the frame's upper tube.

Inlet timing saw a major increase as well with the TD1-B, increasing from 70 degrees BTDC to 90 degrees BTDC. The factory also increased the diameter of the crank in it’s weak area to 25mm, eliminating the breakage problem.

The TD1-B began to win a lot more races than it’s predecessor, with the increased reliability as much as performance improvement to thank for this. Engine mounts cracked, clutches were fragile and the chrome cylinder lining would flake off snagging rings, but the little problems such as these were worth it, these bikes won races against much bigger, well established European machines.

TD1C    The TD1-C was released in 1967. The addition of an inlet “boost finger” machined into the cylinder lining, up either side of the inlet port, as well as corresponding windows cut into the piston to facilitate this porting mod, thinner piston rings, as well as deepening the inlet port and updating the exhausts, took the power output up to almost 40bhp.

Picture: Stan Smith aboard his TD1-C in 1970 at Riverside.

In addition, the wet  clutch was moved to the now traditional position of on the end of the transmission output shaft and had 3 extra plates added.

The huge gap between 1st and 2nd gear was brought back to a more usable size.

1969 was the year when the factory released the new  TD2 (250cc) and TR2 (350cc). One of the main targets of the development team was to ensure that as many parts as possible were interchangeable between the two capacity machines to reduce production costs, as well as encourage wider use of the relatively versatile bikes.

(This is where our story splits into two parts.)

TD2    The TD2's 250cc engine was YDS6  based, producing more than 44bhp @ 11,000rpm from it's 5 port barrel. The exhaust port was raised over the TD1-C as well as being widened, the main transfer was also widened and the main inlet port actually reduced in area. Gone were the “booster port” and the notched pistons with holes in the back. The ring thickness was again reduced, now to 1mm. A new 11mm shorter exhaust also assisted in the increased power.

 At last Yamaha had decided to fit decent Mikuni brand carbs, up to 30mm diameter now, allowing the jetting to be a lot more consistent under both acceleration and deceleration. Surprisingly, the factory opted to include the "Autolube" system and even a kickstarter to the bike, which were immediately removed by the vast majority of serious racers.

Chassis wise, Yamaha cleverly copied the basic layout of the classic Norton "Featherbed" frame with their RD56 works replica unit, why go past a tried and true design? The forks were replicas of the popular Ceriani style. The swingarm though, unfortunately, was mounted on loose fitting, weak, fibre bushes and flexed due to it’s thin walled tubing construction. Brakes were a double twin leading shoe front and a standard single leading shoe rear. The front stoppers had a bad habit of creating a lot of  friction generated heat, which in turn caused the brakes to gradually fade. Yamaha realised this and wisely chose to fit a thumb-adjuster to allow the rider to adjust the free play of the brake lever "on the run". The fuel tank was designed to hold an extra 2 litres of fuel over the TD1C and the seat unit made to house the "Autolube" oil reservoir. At just £ 900, they sold well.

TD2B     An updated model, the TD2B was released in 1971, originally selling for $Aus 1,775. It still had the vertically split crankcases, though the gearing was altered, exhaust ports were widened and main transfers raised and exhausts revised to produce an additional 3bhp at 500rpm more. A few brackets were also changed but not a great deal more.

TD3    1972 saw the appearance of the last official “mass produced” air cooled Yamaha production 250cc roadracer, the  YDS7 based TD3. Overall it was a little disappointing. On paper it, and the 350 TR3, seemed a revelation with their dry clutches, new lighter frames, horizontally split crankcases in common with the 350 as well as an identical crank , 6 speed transmissions, with provision to allow sixth gear to be “blocked out” if rules required it, (though a 5 speed was released initially which also had a wet clutch), gear ratios changed as well.

( Picture once again courtesy of Mitsuo in Japan )

On the track the TD3 suffered chronic detonation problems which were extremely difficult to sort out**. Some of these problems may have stemmed from the un-reliability of newly fitted for this model CDI ignitions.

34mm carbs appeared on spacer blocks. Changes to the motor included reduction in the height and width of the main transfers, increased width of secondary transfers, deepening and widening of the main inlet port, as well as the usual updated exhaust. Output jumped up 2bhp to 49@10,500rpm.
 

 TA250    Early 1973 Yamaha released limited numbers of a TD3 / TZ250 hybrid called the TA250, which was an air cooled TD3 engine housed in a frame which had radiator mounting lugs fitted to it.

 (There are no further details of the TA250  available at the present time. Does anyone have any information at all on this “mystery racer” to share?.)

( ** see below )

TR2    The 350cc TR2 of 1969 was where horizontally split crankcases made their debut on a production racing Yamaha.

Picture: TR2 courtesy of Mitsuo in Japan

Porting design was nothing to write home about and with windows cut into the rear of the pistons, cracks were common and a close eye had to be kept on tolerances and piston condition.

As with all 2 stroke roadracers, reliability and performance only come with detailed attention to cranks, timing and piston ring replacement, plus of course all the other things which go together, the TR2 was no exception. The TR2 shared the same replica RD56 frame as the TD2 and featured horizontally split cases 3 years before the 250.

Picture: TR2B borrowed  from www.vintagebike.co.uk

TR2B    1971 was the year of the updated TR2, named the TR2B. This $Aus 1,923 offering from the factory included improvements such as porting changes, a new conrod, small end, as well as a thinner head gasket, all of which combined to give an extra 2bhp at 10,000rpm.

Picture: Don Emde's TR3

TR3    The last 350cc aircooled production roadracer Yamaha ever produced, the R5 roadbike based TR3 was released in 1972. Changes to the bike including bore and stroke configuration, the engine now sported the 54mm stroke that was to be the mainstay of the TZ range for the next 8 years, a rise in compression ratio, well as a new crank and a 6 speed gearbox replacing the old 5 speed, though as for the TD3, provision to "block out" sixth gear was there. Like it's "little brother" it didn't live entirely up to expectations either, also suffering from detonation and seizures at regular intervals**.  Peak horsepower rose by 2 to 58bhp.

The wheelbase of the TR3 increased by 15mm over the old TR2B while all other dimensions apart from overall length remained the same.

An interesting point: The some of the "works" TR3 engines from 1972 sported 6 transfer ports, like an F/G model 350. It took Yamaha 7 years to let us all in on the secret !!

The good news was the big news from Yamaha later that year, there was a major change on the way ... water-cooling !!

** Saying this, these bikes can be fairly reliable if jetted slightly rich, (though this can hamper performance a little), on good fuel and have ignition timing that isn't too radical, utilising a reliable ignition system. It's usually in very long races that there could be  problems, as with all air cooled two strokes.

Want to convert an R5 or RD350 into a TR3 replica?

Jamie Linxwiler shows you how....         Click Here !!

Click here for a transcript of the Yamaha Performance Bulletin for converting a DS-7 into a TD-3 racer special!!

Click here for a transcript of the Yamaha Performance Bulletin for converting an R-5 into a TR-3 racer special!!

How to tell the difference between the TD2 and the TD3:

(For those of us who have never owned a TD2 or TD3.)

 Once you know the four significant differences it is fairly easy to tell them apart.

Firstly the TD2 had a replica of the RD56 frame whereas the TD3 had the frame from the road bike. 

The main difference is the tube from the top rail down to the swinging arm. On the TD2 it is a gentle curve in true 

featherbed fashion  but on the TD3 it is straighter and goes in at the top.  

Picture: TD2 ( Mitsuo)

Picture: TD3 (Mitsuo)

The next difference is the forks, on the TD2 they are black but on the TD3 they are an aluminum colour.

 The engines probably show the most differences. The TD2 has a tuned engine from the YDS6 road bike with 

aluminium coloured cases, barrels and head, with the fins of the latter smaller and more rounded. The engine in 

the TD3 is from the YDS7 road bike with horizontally split cases and black end covers, the finning is deeper 

and squarer on the head. Finally the fuel tank is looks bigger on the TD3 and is slightly wedge shape sloping 

narrower towards the back whereas on the TD2 the top and bottom edges appear parallel.

( Thanks Roger Gowenlock for the info.)

TD and TR Aftermarket frames.

A handful of chassis manufacturers made frames for the TD and TR range throughout the seventies, click here to read about TD/TR aftermarket frames.

( This special frames page has been available to "Members" since early January 2004.)

Gerard Bidu sent this shot in.

Roughly translated into English: "Well, if it wants to start up then why not!"

If you see anything anywhere in the above information that you know to be in-accurate, or you have something to add, by all means let us know. We're only too happy to receive advice and information on the bikes to enhance the site. Simply  Email the Webmaster with the details.

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03/23/08 10:18 AM +1000    

This website © Greg Bennett 2002.