The 163lb direct-injected two-stroke Ossa Explorer you can’t have

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On paper, it’s a dream bike. How cool would it be to ride around on an incredibly light weight trials bike with a seat? In the real world, there are two problems: It’s not coming to America and, even if it did, its two-stroke wouldn’t be clean enough to meet US emissions.

Adding insult to injury are the Öhlins suspended Enduro 250i and 350i twins that also use the new motor. Ossa is light on info, but they do reveal that both the 250 and 350 weigh less than 220lbs.

Ossa’s direct-injection two-stroke is something we’ve never seen before. It uses two injectors, one in the crankcase and another in the combustion chamber, an ECU controlled power-valve, inhales through an air-box that lives inside the gas tank and expels spent gases through what might be the most complex exhaust ever produced. Direct injection is a big deal because it addresses the problem of unburnt fuel from the incoming intake charge escaping the cylinder through the exhaust port. With direct injection, fuel is added through the cylinder or cylinder head after the piston closes the exhaust port. The only thing in the intake tract is air.

At least, that’s how things would work in a perfect world. The crankcase injector in Ossa’s system pollutes the intake charge with fuel. Not as much as a carburetor would, or even a single injector, but enough to make things dirty. There’s another problem too: It still burns oil. A two-stroke needs either oil in its fuel or a separate oil injection system because the intake charge passes through the crankcase. Ossa isn’t saying how their motor is lubricated, but I’d bet that’s the job of the crankcase injector.

  • Sasha Pave

    The EPA: Killing 2-wheeled fun since 1970(tm).

    • KR Tong

      Hey man thats American beucracy you’re blaspheming. If it wasn’t for the EPA we’d all be choking down toxic air… Oh wait

      • zipp4

        Have you ever been to a major Eastern city? Hong Kong, Beijing, Shanghai… go there and you’ll have a new appreciation for our EPA.

        • aristurtle

          Beijing cleaned itself up for the olympics, though I hear in Shenzen they slice the air up into bricks to refine it into plastic toys.

          • James

            I’ve been living in Beijing for a week now, on a years contract with an international school, and simply cannot believe the pollution. On bad days, we don’t let the kids play outside and visibility is down to a hundred metres. The all seeing eye has to fire the rain rockets to force a rain shower to clear the air and it returns to mean in a day or two, ready to start the cycle again. It’s like wading through a constant cloud of construction dust with the stinging piquance of hot piss.

            Saying that, I’ve never seen a city with such widespread use of electric vehicles.


        • KR Tong

          That requires a bigger discussion, comparing things like cancer rates in Shanghai to ones from Industrial areas like Chanute, KS. I think you’ll agree government regulation sucks—and deliberately sucks—in every country.

          Its not a logical argument to hurt the US motorcycle industry and destroy an entire market in the name of pollution prevention when theres little no regulation of real polluters. I want my two-strokes. Thas all I’m sayin’, yo.

        • randry

          My throat was burning ten minutes after I was there. That and the truck driver taking a dump in the middle of the highway was a rude awakening. I kissed the ground when I got home.

      • Kevin

        I grew up in Southern California in the 1960s and 70s. Anybody who remembers what the air was like back then probably has a different opinion about clean air regulations.

        Seriously, it’s night and day. Trust me, unless you experience not being able to play outside without your eyes watering and your lungs burning, you really have no fucking clue how awful dirty air is.

        • robotribe

          Word. I was elementary school in 1970s L.A. I thought the nuns at my school were just lying to us when they said we couldn’t go out for recess because it was a “smog alert day”.

        • Sasha Pave

          I also grew up in LA during the 70s and there were more smog alert days than school holidays.

          The EPA has done some great things to the LA basin, but the destruction of 2 stroke dirt bikes have little to no effect on those successes.

  • Mark D

    So snowmobiles and outboard motors can be DI 2-strokes…but trials and enduros which would sell maybe 5,000 bikes total can’t have it?


    • Erik

      The trials bike is street legal (check out the tiny perfect turn signals), different emission standards than for offroad equipment KTM still sells two stroke off road bikes in US. It could probably meet on on road emission standards, but it probably costs lots of money to get certified for a bike that might not sell very well.

  • george_fla

    Modern engine materials(bearings,rings,cylinders liners,etc…)need far less oil for lubrication. That coupled with direct injection and me thinks it could run pretty damned clean.

  • fazer6

    That’s some funky swingarm linage going on there.

  • fazer6


  • Scott-jay

    Wanted an Ossa since its Pioneer was hot-stuff (and Bultaco’s were hotter).

  • robotribe

    Do new 2-strokes pass EU emissions requirements?

    • stempere

      If it doesn’t pass US regulation, i doubt it passes Euro3. So yeah where will it be sold then?

      • motoguru

        This is exactly what I was gonna say. Euro standards are way more strict even those of California.

      • Sean Smith

        EU regulations measure emissions. US and California emissions measure how much you have in the bank to pay for testing.

  • daniel

    Is that a side stand on the right hand side of the explorer?

    • Sean Smith

      Yup. It’s a street bike.

  • mugget

    Whoa. Those bikes are so slim.

    Yep – I NEED one.

    Come to Australia my pretties, we’ll have you if the U.S. won’t…

    • Grant Ray

      Why don’t you rub it in a little more? You Australians get all the best toys.

      • quint7

        AND the hottest women. Do you guys still have that insane male/female ratio like the Aussie sailors I met in Hong Kong in 1989 told me about?

        • motoguru

          At least our women have most of their teeth.

      • mugget

        Well I mean we’ve gotta get some good toys down here to keep us occupied, stuck living at the ass-end of the world… haha :P

  • oldblue

    Yes, Ossa, Oz will welcome your slim, sexy, dirty little bikes with open arms.

    Long live the stinkwheel!

  • Coreyvwc

    Outside of KTM those are probably the nicest looking dirtbikes I’ve seen lately. Those hand made expansion chambers are a thing of beauty too.

  • dux

    Those exhausts look like anacondas from outer space! Sick!

  • Penguin

    For alternate seaty Trialsy roady bike take a look at the new GasGas Randonne, 125 4 stroke with full road kit and a removable seat. I would absolutly love a road legal trials bike. Especailly a 2 stroke one.


      Road legal sounds good, but that low weight turns the worry about two guys with a van into one guy with a hatchback.

      • dux

        Or a big dude with a back pack

    • okto

      not legal for the us

  • Chris

    That bike would be super cool to modify into a 2 stroke, street going bobber style bike. Too bad we’ll never get it in the good ol’ us of a

  • nick2ny

    “Fuck the whales, save the 2 strokes!” -everyone

  • Troy R

    2 Strokes are crappy old garbagey pieces of junk…

    With gobs of power.

    For street legal bikes, kill all 2 strokes, but for a trials bike? What does it really matter?

    Of course what this really needs is turn signals and a title.

  • quint7

    It’s funny that Suzuki is pulling out of some race series using the trend towards small bike sales as a reason yet we still can’t get cool small bikes here other than a few niche ones (starter and dirt bikes). I love 200hp 400lb bikes too, but a 50hp 200lb bike that doesn’t fit me like a circus bear sounds like what we old guys used to call ‘fun’. And said ‘fun’ used to come hand and hand with this other word, ‘cheap’.
    The rebirth of the UJM is coming and I’m happy.

  • pplassm

    Ossa is already bringing the trials bikes in, so why not these two? Rumor has it they are much cleaner than current technology 2 strokes. Hell, they burn oil at 100:1.

  • pplassm

    This will probably prod KTM into releasing their in-house developed system on their two strokes soon. You can still register these things, if you try hard enough. :-)

    • Sean Smith

      In Arizona, anything is possible.

  • randry

    Is there a reason why any lean burn or direct injection diesels have never been made for motorcycles? They seem to meet EPA.

    • aristurtle

      There’s a company making a diesel KLR650-derivative for the USMC, but I imagine it would be hard to sell exotic-tech stuff like that in large enough numbers to the general public to pay off the high R&D costs.

  • austin_2ride

    “In the real world, there are two problems: It’s not coming to America and, even if it did, its two-stroke wouldn’t be clean enough to meet US emissions.”

    Evinrude introduced the E-Tec system in 2003. In 2004, Evinrude received the EPA Clean Air Excellence Award for their outboards utilizing the E-Tec system. The E-Tec system has recently also been adapted for use in performance two-stroke snowmobiles.

    Why would Ossa’s direct-injection two-stroke be any differant than BRP’s?

    • Sean Smith

      “Ossa’s direct-injection two-stroke is something we’ve never seen before. It uses two injectors, one in the crankcase and another in the combustion chamber.”

      Said another way: Ossa’s direct-injection two-stroke is different than BRPs in that it adds a second injector, that doesn’t spray into the combustion chamber, but instead into the crankcase, which allows fuel to get into the exhaust. Much cleaner than a carb, but not as clean as a BRPs DI.

      • george_fla

        If there is direct injection of fuel into the combustion chamber why would there even need to be fuel injected into the crankcase?

        • Sean Smith

          “Ossa isn’t saying how their motor is lubricated, but I’d bet that’s the job of the crankcase injector.”

          lol, I don’t want to come off as a dick, but did you guys even read the story?

          • Scott-jay

            Sean writes, “…instead into the crankcase, which allows fuel to get into the exhaust …”
            And, dick asks, Why does crankcase fuel-injector location equal fuel in exhaust?

    • quint7

      Honda was working on bringing back 2 strokes across the board about 10 years ago (maybe 15? God I’m old). I think that the emissions regs along with the removal of 2 strokes from GP racing and the huge leap forward that 4 stroke dirt bikes (re Supercross) took made them decide to pull the plug. If I was one of those pack rats that kept all of my old bike mags I could look it up, but I definately remember following it in the pre high speed internet days (yes, there was a time when getting a picture of a naked girl to download took 3-4 minutes AND it tied up your landline).

      • pplassm

        Believe you are referring to the Honda EXP-2. It was an experimental extreme lean burn engine that competed in and finished the Grenada-Dakar rally, I believe in 1995.

        • pplassm

          The shame is that Honda is the force behind the end of two-strokes, and yet they had the answer to all two stroke problems in their pocket the entire time.

          • Scott-jay

            Environmental preservation is behind the demise of two-strokes, too.
            Once you clean ‘em up; they’re experimental and complex.

  • Taco

    I would feel weird riding a bike that weighed less than me.

    • Chris

      Riding bikes that weigh less then you is tons of fun!

  • Ola

    Yamaha tried something like this a few years ago, was called the Tricker 250. Sold them in Japan and Europe. Was a 4 stroke with about 20 ponies and a weight just over 100kg’s. Never really caught on here in Europe,apparently Yamaha tried to market them as a bike for the BMX generation. Tested one in Barcelona a while ago and it as a blast in congested traffic, way to feeble as everyday bike though.

  • oldblue

    Two strokes ruined me for life. In a good way.

    I grew up riding two stroke dirt bikes. Light, powerful, nimble, they hosed every four stroke available, easily. Way back then we considered four strokes to be a joke.

    I switched to road riding/racing just as road bikes were getting light and fast…the dawn of the GSXR era. I have never seen the point in owning a heavy road bike.

    So today I own a Daytona 675 for the road, mostly because it’s one of the lightest, most agile road bikes available. But I’d love an Aprilia RS250.

    I still have a modded KTM 380 EXC for the dirt. And it will still hang with the big bore four strokes.

    Bring on low emission two stroke bikes, for the dirty AND for the road!