Yamaha Circuit Magazine: DT Range

Text from Yamaha Circuit Magazine, from 1977, Issue 4, detailing the 1978 Yamaha DT range:

 

YAMAHA DT400MX

You can’t really call the Yamaha DT400 "a wolf in sheep‘s clothing" for the bike is one of the toughest-looking on/off road machines ever built. Even so, the description almost fits because the sleek, stylish lines of the DT400 give no hint of the power available from the big two-stroke single.

Fully at home on the street, with the five speed transmission and 29bbp motor giving a more than respectable high-speed cruising ability, the DT 400 comes equipped with all the luxuries of Life. Turn indicators, powerful headlamp. deep, comfortable dual seat, passenger footrests and speedometer / tachometer panel angled at 25 degrees towards the rider for easy vision.

Despite all of these niceties, a single glance at the DT400 reveals that it was destined to do something more than provide transportation to the office (though it would function quite competently in that role).

The monoshock chassis is a direct development of the unit used by Heikki Mikkola to win the 1977 World Championship and the 400cc motor bears a great deal of similarities to the  Championship-winning machine.

The off-road performance capabilities of the DT400 rank on a par with many pure moto cross racing machines and yet the big Torque Induction two-stroke is flexible enough to ride as a trials-type machine!

The reed valve induction aids in this respect and Yamaha Autolube oiling system plus Capacitor Discharge Ignition also combine to make the DT400 unit the kind of reliable power unit that you need if you are going to embark on the kind of long distance cross-country expedition that the big Yamaha seems to invite.

The Yamaha DT400 is meant for the kind of motorcyclist who enjoys his freedom ... the freedom to ride the wide open spaces at speed. But it also gives that motorcyclist a second choice ... a powerful bike for road cruising while flexible enough for commuting.

It is the absolute essence of the dual-purpose machine: capable of completing the International Six Days Trial on the one hand while happily dealing with six days commuting on the other! 

YAMAHA DT250MX

It's not uncomplimentary to suggest that Yamaha's DT250 Enduro machine sets a double standard ... especially when that double standard is the best possible compromise between the demands of street and off-road riding! In each of these areas the DT250 sets riding standards that other manufacturers can only hope to emulate, The superb Yamaha DT-Series power unit has been the subject of constant improvement and development since it first appeared a decade ago. Now it represents the ultimate state of the art in the attempt to design a power unit that will perform as well on the open road as it does on the moto-cross track.

Versions of this have powered Yamaha moto-cross machines to World and National Championships and the latest DT250 features another direct development from the racing scene ... the monoshock cantilever chassis. Proven both in moto-cross and road racing, the monoshock chassis revolutionised the world of suspension development when Yamaha introduced it five years ago. And Yamaha is still the only major manufacturer to utilise the cantilever frame for a volume production machine.

In every respect, the DT250 represents the pinnacle of "dual-purpose machine" development. It has everything that the serious off-road rider needs, including such refinements as unbreakable plastic front mudguards, re-settable trip meter and speedometer for the enduro enthusiasts, a chain tensioner and rubber boots on the front forks to keep out the water and dust.

On top of all this, the 23bhp, five-speed power unit and lighting equipment that meets all Government regulations (it has turn signals too) mean that the DT250 is more-than-respectable performer on the street.

YAMAHA DT125MX

The design of lightweight enduro machines has improved immeasurably over the past few years, with more and more manufacturers realising that not every trail rider wants to manhandle either the weight or the horsepower of the bigger machines on the tough trails.

Yamaha has always offered a top-quality lightweight in its dual purpose Enduro range but there's no doubt that the new DT125MX is more than a match for any comparative machine. It follows the big bikes in the Yamaha DT range in having the monocross suspension chassis that Yamaha designed for its World Championship · winning moto-cross racers. Now that competition technology has been put to work on an Enduro lightweight with staggering results.

Both in the chassis design and in its basic engine specification, the Yamaha DT125MX bears a close relationship to the Yamaha 125cc motocross racers that took Dutchman, Gerard Rond, to Grand Prix wins this year and which earned American National Championships for Bob Hannah and Broc Glover in the past two successive seasons.

This race-breeding is evident in the performance and the handling of the DT125MX ... a machine that is unique in the Enduro field.

It’s a tough trail lightweight that still has full street equipment making it capable of true double duty as a ride-to-work bike during the week and a really effective off-road lightweight whenever the getaway urge hits.

The engine of the DT125MX is based so closely on the engine of the moto cross YZ125 that it even looks the same, with heat dispersant matt black finish, alloy deep-finned head and cylinder barrel. The motor features a racing piston plus competition transfer porting. A high-grade steel crankshaft runs in roller bearings and drives through a multi-plate clutch to the six-speed gearbox.

It is all of this combined with reed valve torque induction that enables the engine of the DT125MX to produce true competition performance with street tractability.

 

YAMAHA DT50

Just like the rest of the famous Yamaha DT Enduro range of dual purpose street/trail bikes, the new DT50 is equally at home on city streets or out in the rough country.

Only difference between the DT50 and its bigger  brothers. as far as capabilities go, is its lack of cubic inches ... and to those riders whose preference is towards lightweight machines, that won't matter a bit.

The DT50 is a genuine endure machine on a small scale; a great little street bike that can carry you way across the city to work or out on the country lanes - but still a bike with true off-road capability.

Sharing the same tough little four-speed, Torque Induction engine as the TY50 trials machine, the Enduro-styled DT50 features a large capacity 6 Litre tank (plus separate oil tank for the Autolube engine unit), braced handlebars and enduro mudguards.

The high level exhaust pipe with heat shield completes the sporting look of this Yamaha ultra-lightweight especially designed with a dual-purpose role in mind. 

Yamaha Circuit Magazine: FS1 & FS1DX

Text from Yamaha Circuit Magazine, from 1977, Issue 4, detailing the 1978 Yamaha range:

YAMAHA FS1 & FS1DX

The smallest of the Yamaha lightweights, the 50cc FS1 and FS1DX combine all the attributes of a big machine in a bright little package that serves as an ideal introduction to motorcycling.

These little sportsters, despite their small size and power output, reflect a lot of the thinking that has taken Yamaha to the top in the racing world.

A rigid pressed steel chassis makes them among the very best-handling machines in the ultra-lightweight class while the 49cc engine zips the bike along at a more than respectable speed.

There is a great accent on safety with the FS1. Waterproof drum brakes on the FS1 and a 203mm hydraulically-operated front disc brake on the FS1DX plus front forks that would do justice to a bike of much larger dimensions. They ell combine to make a machine that, despite its size, gives that real motorcycle feeling.

The sporty image is enhanced by such styling extras as the “speed block " paintwork, the rubber boots on the front forks and the chromed external springs with lively performance and a host of safety features to leave the rider in no doubt that, despite the size, the FS1 still reflects Yamaha’s racing background. 

Yamaha Circuit Magazine: RD Range

Text from Yamaha Circuit Magazine, from 1977, Issue 4, detailing the 1978 Yamaha RD range:

YAMAHA RD400

Yamaha’s most powerful street two-stroke, the RD400, is a direct descendant of the machine`s that made the company's name synonymous with motorcycle sport — the famous and incredibly successful twin cylinder road racers.

Since Yamaha first appeared with their twin cylinder two-stroke power unit over 15 years ago, it has been continually developed and refined to a pitch where it is perhaps the most efficient and powerful middleweight two-stroke machine in the world today.

Cast alloy wheels, disc brakes, CDI ignition, reed valve Torque Induction and Autolube oiling are all part of the RD400 specification.

The sportiest of Yamaha`s middleweights in terms of both power, styling and handling, the RD400 oozes its racebred heritage from every angle. This is confirmed by a ride on the machine, with acceleration. top speed, braking and handling being almost up to racing standards. So close to racing standards, in fact, that the Yamaha RD400 is one of the most popular machines with riders in the production road racing category.

You might not want to take to the racetrack, but if you want all the thrills and excitement that a racebred machine can offer, than the Yamaha RD400 is for you! 

YAMAHA RD250

One of the very first sports machines ever introduced by Yamaha was a 250cc two-stroke twin and it was acknowledged by all as one of the toughest fastest bikes in its class.

Now, over 15 years later, nothing has changed. Yamaha are still making a superb 250 two-stroke, twin cylinder sports machine and it`s still acknowledged as one of the leaders in its class.

Chosen by sporting riders and production racers as the ultimate 250, Yamaha's RD250 has an engine that still has all the hallmarks of its race breeding, The Yamaha 250cc twin cylinder power unit has taken many riders over the years to World Championships and Grand Prix wins and it is still doing just that! The RD250 engine shares many of the features of the racing power units and these similarities show up in its overall performance.

Torque Induction,  Autolube oiling, cast wheels with front and rear disc brakes, a frame based on recent Yamaha racing machines and six speed transmission. All of these things combine to make the RD250 one of the most exciting projectiles in its class. Again!  

YAMAHA RD200

The Yamaha RD200 has established itself in past years at the top of the lightweight street bike field and the 1978 version of the machine continues that tradition in an even more emphatic manner.

Light in weight, easy to handle and economical to run, the RD200 cannot fail to find favour with lightweight fans ... especially those who like their lightweights fast!

The 200cc twin cylinder engine has a direct relationship to Yamaha's Grand Prix winning two-strokes and this shows up in the sparking acceleration and high cruising speed.

Cast wheels and disc brakes emphasise the true sporting nature of the RD200 while rider comforts are not neglected. Comforts like an electric starter and a wide, comfortable seat that would do justice to much bigger machines. Whether you use the lightweight and precision handling to weave through the rush hour traffic to work or if you prefer to play racer on the back roads, the RD200 has to be top of your lightweight list.     

 

YAMAHA RD125

"Good things come in small packages" says an old maxim ... and the Yamaha RD125 is motorcycling proof of that statement!

Howling its way to 10,000rpm, the RD125 has a power unit that is almost identical to machines that, not so many years ago, were winning World Championships for Yamaha. Now those same engines in refined form are providing lightweight enthusiasts with one of the most exciting rides on the road.

The little RD125 is a true sports thoroughbred with its racing heritage moulded into every line. Even the chassis is based on Yamaha racing design and the whole machine handles, brakes and performs in a manner that belies its engine size. It‘s one of the safest, sportiest machines on the road, regardless of capacity and one of the most comfortable too. A wide, comfortable seat that would not be out of place on a big touring machine combines with full instrumentation and adds luxury to the sporting package.

Whichever way you look at it, there's no way the competition can handle what the RD125 has to offer.   

YAMAHA RD50

The little RD50 is Yamaha's smallest sportster and though it's tiny ... it’s tough too!

Putting all of Yamaha's racing experience to work in a scaIed·down package, the RD50 has all the attributes of the bigger sporting machines.