The 1970s half-litre two-stroke twin that’s not Japanese: come and meet Ossa’s amazing Yankee 500SS. Yee-ha!
WORDS: STEVE COOPER PICS: GARY CHAPMAN
It’s 1975 and a callow version of muggins here is at the Racing & Sporting Show in central London. I’m standing slack-jawed, gawping at Ossa’s all-new 500 twin.
I’m currently riding an RD200 and the Spanish bike has a touch of similarity via satin black engine cases and fin’s edges are polished alloy similar to Yamaha’s twins of the period.
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Elegantly-styled exhaust pipes curve tightly around the motor to join a pair of rakishly upswept silencers. A large, but elegantly-styled tank sweeps down to a sleek, minimalist saddle that fails to cover much of the rear guard. Disc brakes were fitted to both wheels, although the front end looks suspiciously Suzuki-esque… and it’s love at first sight!
The unattended stand eventually is staffed by a bored-looking chap who frankly isn’t doing much to sell the product. When pushed about price, dealers, delivery, etc., he almost whispers out the corner of his mouth: ‘If I were you lad I’d go look at Suzuki’s T500 – it’s a much better bet.’
The aforementioned mandible is now on the floor and I walk away disconsolate without even being able to obtain so much as a bloody sales brochure! Miffed doesn’t come close but I’m still looking over my shoulder, desperately intrigued.
That fleeting assignation with the legendary (infamous) Ossa Yankee sets in motion a 50-year mission to actually find another example. This slightly strange Spanish/American collaboration started off as a quest for a powerful dirt-bike which almost succeeded. Sadly, the Yankee Z failed in its target market, then blossomed briefly as a low-level threat to Japanese stink-wheels’ dominance… just as two-strokes were falling out of favour. You really couldn’t make this sort of thing up!
Those timings really couldn’t have been much worse and yet the fates have finally conspired to allow me lots of access to what I’ve always felt was a missed opportunity. Excited? I’m grinning like a loon and almost doing an ‘Eddie from Bottom’ impression with full-on jazz hands as he finds that missing half bottle of Malibu down the side of the sofa. You bet I’m bloody excited. Hello baby!
Martin Kemp’s (no, not from Spandau Ballet) Yankee 500SS is the final iteration of the model and about as good as they get this side of a full resto. What’s there is a top-class combination from the cream of Europe’s 1970s motorcycle suppliers with a soupçon of Oriental in the guise of a Japanese Mikuni oil-pump hidden behind one of the outer engine cases. The Brembo brakes, Veglia gauges and CEV lights are Italian – the rear indicators are currently Honda at the moment whilst originals are being sourced.
The wheels are also Italian in origin and probably Campgnola. Spanish suspension firm Betor have supplied the springy stuff at both ends and much of the rest is also from the Iberian Peninsula, with the CDI ignition system made by Motorplat of Barcelona. And because the power unit is a pair of 250 trails/scrambler singles effectively nailed together, there’s one pick-up at each end of the crank.
Something I’ve never encountered since I started riding, is the Ossa’s switch-gear which comes from the same factory as the ignition. It’s a curious combination of Lucas-style flippers mixed with a Euro-take on contemporary Japanese kit. One key deviation from stock is the use of Mikuni aftermarket carburettors; the previous owner fitted these easily-sourced and tuned units in preference over the uber-rare German Bing units fitted as standard. Another not so obvious upgrade is the fuel tank which is a steel reproduction of the original fibre-glass unit, but if owner Martin hadn’t told me I’d have been none the wiser.
The Yankee you see is one of just 1500 or so produced between 1976 and 1979 and has the odd fitment that vaguely smacks of a homemade special, i.e. the chain-guard: but apparently they all look like that. However, for a small company struggling to compete in a post-Franco, open market Europe, it was a damn fine job. Stylistically, there’s more than a hint of period Ducati or Benelli about it and I reckon it wears its looks rather well… but, of course, I may just be a little biased.
The factory strove to deliver its own styling cues whilst still trying to stay relevant, topical and on-trend. The dash-panel with its azure blue-faced gauges and those alloy bezeled idiot lights is like little else. The silver tank and side-panels picked out with yellow and orange flashes helps mask the bulk of the satin black motor, and check out the springs on the Betor shocks… no one else colour-matched springs with body panels!
Starting is simple and essentially no different to a Suzuki T500/GT or Yamaha RD400, which are the obvious comparators. The only subtle difference is liberating the kick-start lever whose rubber top nestles in-between the fins of the right cylinder head when not in use. Once running and the chokes off, the motor sounds like any other large-capacity two-stroke twin – or more accurately, perhaps, a pair of 250 singles running in unison. The motor is rubber mounted and probably needs to be as it jumps around a fair amount at tick-over, not unlike an MZ 250 single. Get it to two grand on the tacho and it smooths out beautifully. The air-box is suitably muted and the exhaust note restrained, giving the bike a genuine air of sophistication.
If the bike has an Achilles heel it has to be the gear-change which is unlike anything else I’ve sampled – owner Martin admits it takes some getting used to and I fully accept that. The action is best described as ‘knife-through-greased-marbles’ rather than peerless. There’s nothing actually wrong with the selection process but it’s not Oriental-smooth, yet always remains the right side of agricultural. Perhaps the biggest issue is the pedal itself, which is factory-correct yet decidedly not ergonomic. It’s designed as a heel-and-toe lever for some utterly uncountable reason. Furthermore, its geometries are plain whack-job.
Take a look at it and ask just why you’d mount the parts your foot touches off a lever mechanism that hangs down from the actual selector shaft? The pedal’s action is odd as it moves around the pivot/fulcrum, giving a rocking-cum-seesaw motion. With practice it’s workable, but as the man said, ‘That just ain’t natural, boy!’ A cursory wiggle of the shaft end twixt thumb and finger clearly demonstrates there’s no discernible slop internally so I guess that’s how they all are. Looking online at examples owned long-term, it’s interesting to see some owners have dropped the OEM pedal and crafted something more traditional in place so the action is more direct and not so convoluted. Therefore, I’m strongly betting there’s a better change to be had at the end of a more orthodox gear lever.
Enough obsessing about one facet of the Ossa – what about the rest of it? Divine, utterly divine, and I rarely use that adjective when discussing motorcycles. What we have here is a machine with substantially better road manners than anything out of Japan for the period – the quality of the handling has to be experienced to be believed. And better still, that suspension works in ways even the Italians had yet to master. The frame/springing set- up is firm but not harsh; there’s compliance allied to feedback along with comfort that would make a Ducati owner weep! The seat is just about perfect; the handling nimble but not skittish. And it weighs 21 kilos less than the previously mentioned Suzuki. And it’s also 13 kilos lighter than Yamaha’s RD400!
As for braking, well, need you ask? With a trio of twin-piston Brembos biting down hard on cast-iron discs it’s all you could ask for and more. The lowish bars combined with a near-perfect riding position make for a stunning experience. Power delivery is exactly what you might expect and there could be more performance to be had… at a price. A couple of two-stroke experts I know have seen inside Yankee motors and reckon what’s there is good in terms of porting, but gas flow could be improved.
The biggest impediment to getting the bike to its true potential is those gorgeously angled exhausts. Very much form over function, those that know reckon they need a better cone design combined with a more voluminous expansion section. Thus equipped, Ossa’s big twin would really be flying and the changes wouldn’t seriously impact that drop-dead gorgeous profile.
I was always going to be positively-biased towards this machine and no doubt it shows. However, it goes to show what small factories could do before the big corporations stifled such creative genius. As it stands now the Ossa Yankee sits somewhere between Yamaha’s 400 and Suzuki’s 500, yet with handling that knocks both into the long grass. With a decent set of road-complaint chambers and a sensible gear pedal you’d be seriously hard pushed to better the best air-cooled two-stroke twin that never quite made it!
Owner’s story – Martin Kemp
I first saw a picture of an Ossa Yankee in Mick Walker’s Spanish Post-War Road and Racing Motorcycles book and I immediately liked the look of the bike.
It took me another 20 years to track one down. They are extremely rare in the UK. Around 1500 were made, mostly sold in Spain, a few in France and Italy. I know of only two others in the UK.
Back in 2004 I bought an incomplete wreck of an Ossa Yankee at the Netley Marsh Eurojumble, with a view to restoring it. However, life, work and other bikes got in the way and nothing happened. Then in late 2018 I saw this bike for sale on a well-known auction site. I rang the seller who told me that the bike needed some work before he would sell it.
It took until March 2019 to actually buy the bike, and for the first few months I rode it until the centre crank seal started leaking, with plumes of smoke coming out of the left-hand silencer. These engines are full of shims and the two cranks are a taper fit to each other.
Engine disassembly requires many special tools. Fortunately, I was able to borrow them from a guy who sprints a Yankee. I then entrusted the engine rebuild to Nametab Engineering in Redditch who did a first-class job of rebuilding it.
Since then I’ve regularly ridden the bike, and I am very pleased with it. The brakes and handling are really good, the motor goes well, though more like a GT than a RD, and with decent 12V lights, electronic ignition and a Mikuni oil-pump and carbs (originally they would have been Bing), it is a lovely bike to ride. The gearbox isn’t as slick as that of a Japanese bike, but I’ve got used to it.
And I know that whenever I ride it to a bike meet, there is zero chance that anyone else will turn up on one!
Inception, reconfiguration and racing
The Spanish firm initially manufactured cine projectors in the 1920s, taking its name from the initials of Orpheo Sincronic Sociedad Anónima, hence Ossa.
Motorcycle production commenced in 1949, centred on a successful range of single-cylinder two-stroke machines. With leisure motorcycling becoming popular in the USA, Ossa found a ready market supplying reliable stroker singles. The one thing the company absolutely refused to contemplate was a multi-cylinder machine. They raced their hugely competent singles at GP level and achieved their greatest successes in Grand Prix road racing, competing with an innovative monocoque-framed bike. Santiago Herrero won four 250cc Grand Prix with Ossa before being killed while competing at the 1970 Isle of Man TT.
Designer Eduardo Giró was keen to build bigger and better, and had an unlikely ally. Eventually granted permission to build a twin, this was achieved by joining a pair of singles together via a pair of tapers. With little funding or corporate will to progress the concept, help came in 1969 from the US Ossa importer: the Yankee Motor Company.
This enterprising team saw the potential for a powerful lightweight 500 twin to compete in enduros, desert racing and the like. Helped by Dick Mann of oval racing fame, the collaborative project got underway.
Sadly, delays in production ultimately caused the demise of the Yankee Z, which was commercialised too late. Lighter motorcycles were making their way into the American market from Japan and the Yankee Z was too bulky for serious competition so production was axed.
With fewer than 800 sold, someone at Ossa decided that they ought to salvage something from the project and thus the Yankee was born. Many changes were made to the original set up, leading to the bike we have tested. Unseen, but definitely the most significant was the rephrasing of the motor. In its American guise the big twin ran a 360-degree crankshaft which must have thrown out some serious vibrations, but when reworked in Spain the motor was swapped to the more conventional 180-degree layout.
In various formats Ossa even went racing with the Yankee. A 460cc prototype with Oldani brakes was entered in the 1968 Barcelona 24-hour endurance race but was forced into retirement early on.
Serious efforts were made to road race the bike in a 448cc format at various levels with mixed success, but Ossa went a step too far with one particular endeavour. Bolting a pair of 448cc twins together to create a 976cc four was simply too much for the existing running-gear.
Utterly unsuited to a surmised 90+bhp, the chassis tied itself in knots at Montjuic Park before dumping the rider on the ground, buckling its wheel and almost snapping the forks off. After that episode Ossa left racing the big twins to dedicated privateers!
Specification
ENGINE TYPE: 488cc, air-cooled, piston-ported, two-stroke twin
BORE AND STROKE: 72.0mm x 60.0mm
CLAIMED HORSEPOWER: 58bhp @ 7500rpm
MAXIMUM TORQUE: N/A
TRANSMISSION: 6-speed
COMPRESSION RATIO: 8.1 (uncorrected)
CARBURATION: 2 x Bing 27mm BING (Mikuni fitted on test bike)
BRAKES: 2 x disc (F), 1 x disc (R)
TYRES: 3.25 – 19 (F) 4.00 -18 (R)
DRY WEIGHT: 158kg (335lb)
FUEL CAPACITY: 4 gallons (18 litres)
