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Trevitt's Blog: Can Two-Strokes Make a Comeback?

KTM and Husqvarna recently announced that they will be producing two fuel-injected two-stroke models for 2018, as part of their respective enduro lineups. (The Husqvarnas will be essentially rebadged KTMs, as are most of the company's models.) While most manufacturers, including KTM and Husqvarna, offer a range of two-stroke dirt bikes, there have been few two-stroke street bikes of any note since the demise of the Yamaha RZ350 in the mid-nineties. The KTM and Husqvarna announcements, even though covering enduro models, could be the beginning of a trend that sees two-strokes making a comeback in the on/off-road market, and perhaps eventually street bikes.

Two-strokes offer less weight, fewer moving parts, less friction and - of course - twice the number of power strokes than four-strokes, for substantially more performance in a given displacement. On the downside, however, emissions and fuel economy are significantly worse. There are two issues here: One is that in the two-stroke cycle, the transfer ports (that "transfer" the fuel/air mixture from the crankcase into the cylinder) are open at the same time as the exhaust port, and for a significant portion of the cycle. During this time, unburnt fuel can go directly out the exhaust, affecting emissions considerably. The second issue is that, because the fuel/air mixture in a conventional two-stroke passes through the crankcase, the lubricating oil for the big-end and main bearings ends up being burnt along with the fuel, also affecting emissions. The writing was on the wall for two-stroke street bikes in the early eighties, with increasingly strict emissions laws being more and more difficult for the manufacturers to comply with.

In the mid-nineties, Bimota manufactured the V-Due, a 500 cc two-stroke V-twin street bike. The V-Due worked around the emissions issues by using fuel injection and forced lubrication for the bottom end. Ideally, a two-stroke would use direct fuel injection, where fuel is injected into the combustion chamber (rather than the throttle body) after the exhaust port is closed, to minimize emissions. This technology has issues of its own, however, and the V-Due used transfer port injection. While not an optimum solution, in this setup only air goes through the throttle body, into the crankcase and up the transfer ports; the fuel is finally injected in the transfer ports, where it can't pick up the lubricating oil. As well, the exhaust port can be almost closed when the fuel is introduced, minimizing how much goes directly out the exhaust unburnt.

With a separate lubrication system for the V-Due's bottom end, and only air going through the crankcase, the amount of oil that made it to the combustion chamber was also minimized. While the bike did pass US emissions standards at the time, it had significant issues with rideability attributed to the fuel injection, and eventually the system was scrapped altogether in favour of carburetors. Even then the model had continuing issues, and was largely blamed for the company's bankruptcy.

While little was revealed in the KTM and Husqvarna press releases, the KTM version did indicate that the new bikes use transfer port injection, like the V-Due. Certainly the technology has progressed significantly since the V-Due's time, and KTM promises "a completely new experience in terms of power delivery and rideability." KTM, and other manufacturers, have surely been working on two-stroke fuel injection for some time, and the technology is very common in the marine and snowmobile market. If the new KTMs deliver on those promises of rideability and power delivery, it may open the floodgates for the other manufacturers to follow suit.

What will the holdup be for street bikes? The RZ350 and V-Due had a difficult time meeting the relatively relaxed emissions standards of their time, and the current Euro 4 standard is extremely difficult even for clean-burning four-strokes to meet. Load up a two-stroke with direct injection, an elaborate lubrication system, exhaust valves and other extras to meet today's standards, and cost, weight and complexity quickly approach the four-stroke realm. (Note on the image above all the extra equipment tacked onto the cylinder of the KTM engine.) Additionally, in the last 20 years since the V-Due, four-stroke technology has improved considerably and closed the gap to two-stroke performance.

The media launches of the new KTM and Husqvarna models are mid-May, at which time we'll know more about the technology used and if it could potentially be applied to street bikes. It may be wishful thinking on my part, but I don't think I'm alone in wondering how something like an up-to-date RZ500 would compare to a current four-stroke litrebike.

Friday, 07 April 2017 12:16 Published in Andrew Trevitt


Husqvarna Motorcycles Introduce Fuel-Injected 2-Stroke Enduro Models

(April 4, 2017)- Husqvarna Motorcycles proudly announce the introduction of their next generation fuel-injected 2-stroke enduro motorcycles.

Tuesday, 04 April 2017 18:57 Published in News


American Flat Track Names Husqvarna Motorcycles As Official Motorcycle Of AFT Singles

DAYTONA BEACH, Fla. (Feb. 16, 2017) – American Flat Track is proud to announce a new partnership naming Husqvarna Motorcycles as the Official Motorcycle of AFT Singles for the 2017 season.

Thursday, 16 February 2017 15:34 Published in News


The Husqvarna Motorcycles 701 SuperMoto Ride Out Moves Up A Gear In 2017

@Husqvarna1903 •#701SuperMotoRideOut •(February 8, 2017)- Husqvarna Motorcycles is pleased to present the second edition of the 701 SUPERMOTO RIDE OUT, four days of exciting riding aboard the 701 SUPERMOTO.

Wednesday, 08 February 2017 13:16 Published in News


Husqvarna introduces production Vitpilen 401 and Svartpilen 401 models

Husqvarna Motorcycles took the covers off its production VITPILEN 401 and SVARTPILEN 401 machines, while also introducing the all-new concept VITPILEN 401 AERO at the 2016 EICMA show held in Milan, Italy. These three new models form part of Husqvarna’s exciting new range of ‘Real Street’ motorcycles.

With the introduction of these three pure state-of-the-art models, Husqvarna Motorcycles takes an important step towards fulfilling its progressive vision of street motorcycling.

The first two models of the ‘Real Street’ range will be the VITPILEN 401 and SVARTPILEN 401, with Husqvarna Motorcycles fully focused on rolling them out at authorized dealers by late autumn 2017. True to the brand’s high quality, performance and design standards, these two models pave the way for an astounding future in the on-road segment.

Also launched at EICMA 2016 is the VITPILEN 401 AERO concept, a single-cylinder machine that is the perfect interpretation of what a 21st century faired motorcycle should look like, according to Husqvarna.

VITPILEN 401
Launching Husqvarna’s new ‘Real Street’ range, the VITPILEN 401 is a refreshingly simple and progressive urban street motorcycle that provides a new gateway into the motorcycling culture for a wider range of riders. Recognized and globally awarded for its unique design, the VITPILEN 401 presented at EICMA 2016 is set to hit the showrooms by late autumn 2017.

Devoid of any excess and focused on providing a pure riding experience, the VITPILEN 401 features a technologically advanced single-cylinder 375 cc engine that is housed in a stripped-down but progressive layout. Offering excellent performance, the bike appeals to an entirely new generation of riders looking for an honest and highly accessible machine.

VITPILEN 401 HIGHLIGHTS:
=>Pure & progressive design
=>Sleek bodywork forming clean lines
=>Accessible riding position
=>Modern fuel-injected 44 hp engine
=>Lightweight steel-trellis frame
=>Unique steel-aluminium exhaust
=>9.5 litre fuel tank
=>Long single seat
=>Premium LED lights
=>WP suspension
=>Slipper clutch
=>Bosch 9.11MB two channel ABS system
=>Sporty clip-on handlebars
=>Street-focused Metzeler M5 tyres

SVARTPILEN 401
Forming part of Husqvarna’s ‘Real Street’ bike range, the SVARTPILEN 401 is a modern day interpretation of a street explorer. Featuring a bold and rugged appearance it offers a progressive new way for potential riders to experience motorcycling.

Beyond its unique styling the SVARTPILEN 401 has a high focus on everyday functionality thus featuring rugged knobbly tyres, a practical tank rack and more robust protection all-over.

Built around a similar chassis and engine philosophy to its VITPILEN 401 sibling, the SVARTPILEN 401 offers a more upright riding position thanks to its wider motocross-styled bars. The finished version of the SVARTPILEN 401 presented at EICMA 2016 is also expected to hit the showrooms by late autumn 2017.

SVARTPILEN 401 HIGHLIGHTS:
=>Rugged street explorer
=>High focus on functionality
=>Standard skid plate & tank rack
=>Two single seats with high-quality fabric
=>Modern fuel-injected 44 hp engine
=>Lightweight steel-trellis frame
=>Unique exhaust with robust protector
=>9.5 litre fuel tank
=>Premium LED lights
=>WP suspension
=>Slipper clutch
=>Bosch 9.11MB two channels ABS system
=>Wide offroad style handlebars
=>Pirelli Scorpion Rally STR tyres

VITPILEN 401 AERO
Drawing inspiration from the brand’s iconic past the VITPILEN 401 AERO is a compact single-cylinder ‘Real Street’ concept motorcycle that ideally depicts Husqvarna’s interpretation of how a faired bike should look like.

Offering an innovative design approach, the VITPILEN 401 AERO concept features an aerodynamic fairing that seems to have been moulded by the wind itself. With every part of its windshield being purely technical, increased amounts of air are now channelled through to the engine to regulate cooling.

Compared to its VITPILEN 401 sibling, the all-new windshield gives the AERO a fuller appearance while allowing the front and the rear ends of the bike to perfectly match each other. With the design of the windshield now encouraging a more locked-in position, the rider’s helmet becomes part of the airflow in what is a fully immersive riding position.

The VITPILEN 401 and SVARTPILEN 401 production models, as well as the new VITPILEN 401 AERO concept motorcycle will be on show for the duration of the 74th EICMA in Milan on the Husqvarna Motorcycles booth, Hall 18 booth M60.

Tuesday, 08 November 2016 16:22 Published in Industry News


Husqvara Unveils 2017 Apparel Collection

@Husqvarna1903 •@HusqvarnaNA •(October 26, 2016)- The latest Husqvarna apparel range, which embraces a full selection of functional apparel for off-road casual and lifestyle apparel and accessories, can be seen on the Husqvarna Motorcycles website.

Wednesday, 26 October 2016 16:18 Published in Industry News


Husqvarna Motorcycles Introduces Updated 701 Supermoto & 701 Enduro

@Husqvarna1903 •#husqvarna •(September 29, 2016)- Husqvarna Motorcycles is proud to unveil the new 701 SUPERMOTO and 701 ENDURO, two class-leading single cylinder motorcycles that have been significantly revamped for model year 2017.

Thursday, 29 September 2016 13:36 Published in Industry News


Husqvarna Motorcycles launches the 701 Supermoto microsite‏

Husqvarna Motorcycles is happy to introduce the 701 Supermoto microsite. Dedicated to everyone who fell in love with the latest Husqvarna street machine recently introduced at 2014 EICMA, the brand new 701 Supermoto microsite will unveil a whole lot more information and insights in the coming weeks and months. The 701 Supermoto is due to be at official Husqvarna dealers in November 2015.

Users that register directly with the microsite will be the first to receive a dedicated newsletter every time new content is added to the microsite. In doing so, they will discover, piece by piece, the exciting features of the first street machine of Husqvarna's new era.

Visit www.701supermoto.com

From: VICTORIA HETT // MARKETING SPECIALIST

Tuesday, 28 April 2015 13:15 Published in Products


BMW Sells Husqvarna to Pierer Industrie AG

Almost hidden in a press release we received from BMW (full release below) was the following line:
"...the BMW Group signed a purchase agreement with Pierer Industrie AG (Austria) for the acquisition of Husqvarna Motorcycles."

Who is Pierer Industrie AG? Among other things, they are 51% owners of KTM.

Friday, 01 February 2013 09:53 Published in Industry News


Inside Impression: Husqvarna TR650 Terra & Strada Review

The sun is coming up on the rolling hills of southwestern Spain, and that’s a good thing.  We’re riding on sweeping, bumpy, mostly secondary back roads, and our pace has been somewhat beyond the typical motorcycle headlight’s capability.  A little more light, overall, will definitely take some of the drama out of this jaunt.

Tuesday, 08 January 2013 13:21 Published in Feature Stories