How to buy the best Yamaha DT125/175MX
Not fast, not flash, but Yamaha’s DT175MX and its DT125MX sibling still tick plenty of boxes for those who value versatility and fun factor
Yamaha could make a plausible claim to be the inventors of the modern trail bike. Their 1968 DT1 250 was probably the first genuine trail bike (rather than street scrambler) and it changed the face of the lightweight motorcycle market. Remarkably competent on the dirt, the DT1 was fully equipped for the road, too, with efficient lighting, Autolube lubrication, decent brakes and even (optional) indicators. And it created a new class of recreational off-road riders in the USA.
The trail bike genre swiftly spread across the globe and, five years after the launch of the DT1 in America, Yamaha’s DT range had expanded dramatically. That year, the DT175 debuted in the UK, and soon became a firm favourite. Fastforward another five years, to 1978, and it took a major step forward with the launch of the monoshock DT175MX.
With styling based on the factory’s world-beating motocross bikes, the MX was even more of a hit than its twinshock predecessor. Young learner riders loved its looks, while a surprising number of active trail riders warmed to its simplicity, rugged dependability and genuine off-road performance. While many DT owners may not ever have ventured off-road, some of those who did proved the competence of the DT beyond doubt. London Yamaha dealer Dave Raynor rode a lightly modified DT175MX to a Gold Medal in the Welsh Two Day Trial and plenty of the new DTS were providing their happy owners with a competitive – and affordable – ride in the clubman class of their local enduros. Trail riders loved the bike, road riders loved it, even the press loved it, with Bike’s Mark Williams declaring it the best Japanese trail bike ever.
Yet, for all the DT175MX’S success, it was a fairly simple and logical progression of Yamaha’s tried and tested DT formula. Aside form the six-speed gearbox and the cantilever rear suspension – borrowed from Yamaha’s motocross range – there wasn’t much new about the MX. The engine was a conventional seven-port, reed-valve induction unit, pumping out a useful 17bhp – nothing new for Yamaha. That slim monoshock frame was the big selling point, but again it was something Yamaha had plenty of experience with from their motocross involvement. If anything, it was the little details that made the MX model such a great all-rounder. Serrated, folding footrests, snail-cam chain adjusters, a tucked in, high-level exhaust, electronic ignition, tyre security bolts and flexible indicators. The MX had been designed from the outset as a genuine trail bike. Development of the DT175MX was limited – probably because it was pretty much right first time. There was a vented front mudguard for 1979 and a switch to a box
section swingarm (reflecting developments to the YZ motocross range) in 1980 – when the DT125MX joined the 175 in the Yamaha line-up – which necessitated a revised frame and airbox, too. Apart from that, though, changes to the MX were limited to the annual round of paint and graphic updates. And, even though the DT125/175MX gave way to a new, liquid-cooled DT125 (in the UK at least) at the end of 1980, the basic design soldiers on to this day in some markets.
Simple, affordable and effective. The DT175MX and DT125MX remain as desirable now as they were in their heyday. A few years ago, you could pick a nice one up for a few hundred quid. Now, it’ll probably cost nearer £2000 – and more for a real belter. We’d say that’s still not bad value for one of the best lightweight all rounders ever.