Classic Motorcycle Mechanics

YAMAHA DT1

This month – the first genuine adventure motorcycle. Honest, it is…

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Scoop’s guide on an early trail iron!

Back in the mid-1960s American motorcycli­sts were substantia­lly ahead of the Europeans when it came to having fun on two wheels. While we used motorcycle­s mostly for commuting and as the family’s main form of transport our colonial cousins were already treating the motorcycle as a leisure device. With vast off-road areas readily available, Joe Average could ride almost unhindered wherever he liked. Yamaha, like its competitor­s, had already offered novice friendly dirt bikes from 50 to 100ccs with the likes of the Omaha step-through and the Trailmaste­r. These and machines such as Suzuki’s Hillbilly and Honda’s various SL machines did an okay job but never really excelled; they were (after all) only road machines very subtly modified. There was a place in the market for better, more competitiv­e dirt bikes which firms such as Ossa, Montesa and Bultaco had sought to fill. The Spanish bikes were essentiall­y hand-built and supplied via an uncertain and sketchy dealer network that offered haphazard support and variable levels of spares. Yamaha USA formed a small focus team and evaluated Montesa’s 250 Scorpion and Bultaco’s Campera and Matador machines. Fortuitous­ly, Yamaha Japan happened to have a 250 stroker motor originally intended for motocross use which they detuned and flew Stateside. From here the Americans built what they felt their market needed and sent the result back to the R&D team in Iwata.

What followed was a series of motorcycle­s in various forms of developmen­t being sent back and forth across the Pacific Ocean until an agreed production prototype was finalised. The resultant machine made its debut at the 1967 Tokyo Motor Show and totally wrong-footed the opposition. Launched early the following year, the DT1 proved to be an instant hit in both America and Australia which Yamaha saw as its most significan­t markets. Some 800 machines were initially earmarked for the USA and they were snapped up almost as soon as they came off the ship. Within the first two months Yamaha had to up its manufactur­ing schedules to 1500 per month and then 2500 which was the plant’s maximum capacity. Potentiall­y the DT1 didn’t necessaril­y offer anything that hadn’t been on sale before with various disparate manufactur­ers. However, the American and Japanese teams managed to get all of the best off-road attributes into one machine, something that had never happened before. A big plus was the use of oil injection courtesy of the Autolube system; no more messing around with premix. The frame was robust and arguably overengine­ered or even too heavy but it didn’t break in use. The exhaust was out of the way, the cleated foot pegs were hinged, the swingarm was box section for maximum rigidity, a decent bash plate protected the power unit, two transmissi­on cush drives aided low speed usability and Yamaha had even fitted grab rails to assist extraction of the DT from bogs and quagmires. In a nutshell this was one seriously well thought out machine. Knowing that many DT1’S would be used in outright competitio­n, Yamaha was ready with its GYT Kit (Genuine Yamaha Tuning) which added a frankly phenomenal 10bhp and an additional 1500 extra rpm. Out of the crate this was the best dual purpose machine built to date! Was the bike without issues? No, and to underline that very point the DT1 remained a work in progress throughout its life. In fact our bike in camera has various subtle discrepanc­ies that cover the range of factory changes, modificati­ons and upgrades the model endured in its lifespan of 1968-1969. To even dare to launch the DT1 was a brave move by Yamaha and so it was inevitable there’d be a raft of small tweaks necessary as customer and dealer comments were fed back to the factory. By modern standards the Yamaha DT1 wouldn’t cut the mustard off-road any more yet it will still work as Yamaha intended. The DT1 is an inestimabl­y significan­t machine and without it we might not have had the various AT, CT, RT models or, indeed, the entire later DT range. Yamaha’s courageous decision galvanised Suzuki to launch it TS range and Honda to latterly develop and launch the XL series of off-rad machines. If you get the opportunit­y to sample a DT1 you’ll almost certainly marvel at just how user friendly 50-year-old trail bikes can be. Yes they really are that good.

 ??  ?? INDUCTION SYSTEM If the air-box is missing, expect to see bore wear, maybe bad enough to require a re-bore. TANK BADGES OEM NOS examples sell for at least £100 each with decent reproducti­ons working out a £75 a pop! TIN-WARE It really does need to be...
INDUCTION SYSTEM If the air-box is missing, expect to see bore wear, maybe bad enough to require a re-bore. TANK BADGES OEM NOS examples sell for at least £100 each with decent reproducti­ons working out a £75 a pop! TIN-WARE It really does need to be...
 ??  ?? EXHAUSTS Repairing one of these that’s full of holes and carbon is not an easy win. ELECTRICS Basic 6V system needs to have decent earths and connection­s to get the best from it. ENGINE Very reliable as the motor is not highly tuned unless they’ve been...
EXHAUSTS Repairing one of these that’s full of holes and carbon is not an easy win. ELECTRICS Basic 6V system needs to have decent earths and connection­s to get the best from it. ENGINE Very reliable as the motor is not highly tuned unless they’ve been...
 ??  ?? Even if seized it’s worth saving.
Even if seized it’s worth saving.
 ??  ?? All you really need out on the trail.
All you really need out on the trail.

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