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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


Exclusive MotoGP Season Preview: Is Vinales Ready?

The 2017 racing season gets fully underway this weekend under the lights, in the desert at the Losail Circuit in Qatar, at the first of 18 scheduled MotoGP rounds. After a crazy 2016 season with an unprecedented nine race winners, attention at the top tier of motorcycle racing is steadily building.

Friday, 24 March 2017 11:51 Published in Feature Stories


Ride review: 2017 KTM 1290 Super Adventure R! (with photos)

For the international launch of its flagship new adventure model, the 2017 1290 Super Adventure R, KTM picked the desert landscape of Paracas, Peru, four hours south of the capital city Lima. The desert terrain doesn’t reflect what we typically encounter here in Canada, but with this region having hosted Dakar stages in 2012, we knew that there were going to be excellent opportunities to test the off-road capabilities of the R version of the 1290 Super Adventure.

Thursday, 23 March 2017 16:51 Published in Feature Stories


KTM Releases 2017 RC Cup Racebike Details

@ktm_canada • @KTM_RCCup • @ama_racing • (December 2, 2016)- KTM Motorsports is pleased to announce important details about the KTM RC CUP RACEBIKE that is now available for purchase for participants of the KTM RC Cup, held in conjunction with the 2017 MotoAmerica Racing Series.

Friday, 02 December 2016 15:56 Published in Industry News


KTM Canada Welcomes RC Cup Rider Alex Dumas To Their Orange Family For 2017

@ktm_canada_official •@alexdumas_racing69 •(November 18, 2016)- KTM Canada, Inc is happy to welcome Alex Dumas in the Canadian orange racing family for 2017.

Friday, 18 November 2016 15:58 Published in News


KTM reveals revamped 390 Duke and 1290 Super Duke R

KTM introduced revised versions of its naked 390 Duke and 1290 Super Duke R at EICMA in Milan, Italy on November 8. Building off the success of the adventure range released in Cologne, Germany last month, KTM continues to increase the versatility and performance of each individual bike, ensuring that everybody is able to find just the right KTM for their specific requirements.
 
KTM 1290 SUPER DUKE R – THE BEAST 2.0 – NOTHING BUT THE BEST
Every part was reconsidered to perform on and off the racetrack for a truly READY TO RACE motorcycle. The innovative construction of the new LED headlight ensures that no unnecessary additional parts or weight are added. The new multifunctional TFT-dashboard displays all important information in a clear and bright display. A tremendous power-to-weight ratio ensures a dominating performance in any situation. The 1290 SUPER DUKE R now bristles with more power thanks to reworked cylinder head and intake, while new electronic features allow for class-leading rideability and convenience.
 
KTM 390 DUKE – CORNER ROCKET
New, aggressive styling proclaims that the 390 DUKE is a READY TO RACE naked motorcycle with the performance and handling to back it up. The bodywork is sharp and modern with a slammed, predatory stance. Up front, a new LED headlight and bright, full-color TFT digital dash boast features not found in this class of motorcycle. At the rear, an exposed bolt-on subframe sits below the redesigned seat and pillion. A new form-fitting 3.5-gallon steel fuel tank increases the 390 DUKE’s range. Putting the power to the ground is now smoother and more controllable than ever before thanks to the new ride-by-wire throttle. That power, combined with a steel trellis frame, a new 43 mm WP upside-down fork and a larger, more powerful 320 mm front brake rotor take the ride to the next level.

Tuesday, 08 November 2016 17:19 Published in Industry News


KTM Reveals New Adventure Lineup For 2017

@intermotcologne • #intermot @KTM_Racing • Cologne (October 4, 2016)- KTM revealed an updated Adventure lineup for the 2017 model year at Intermot on October 4. This includes brand-new 1090 Adventure and 1090 Adventure R models, as well as three versions of the 1290 Super Adventure.

Wednesday, 05 October 2016 21:04 Published in Industry News


KTM introduces new RC 390

KTM has unveiled an exciting new sport bike for the 2015 season, the RC 390. Inspired by the track-ready RC8 R superbike, the 390 is also race-ready, and with 44 hp and a 147 kg weight, we expect it to be one fun little machine. One thing's for sure - we want to ride one, now.

Thursday, 04 September 2014 15:01 Published in Industry News


KTM claims new 'cornering ABS' makes the 1190 Adventure the "world's safest motorcycle"

The 2014 KTM 1190 Adventure and 1190 Adventure R feature a truly revolutionary rider assistance system: the riding dynamics control MSC (Motorcycle Stability Control). This system makes a long held dream come true – ABS that even works perfectly while cornering.

Thursday, 26 September 2013 14:50 Published in Industry News


Product intro and Q & A at Mission Cycle

If you have been in recently, you probably already know about our 2013 product introduction / information night.  If you haven't, then here it goes...

Read MoreOn Thursday, March 21st from 4-7pm, we will have two industry reps here to talk shop.  One is from Motovan, our largest aftermarket supplier; and the other from KTM.

Jesse, from Motovan, will be here for any 'q and a' you have on their product lines.  On Thursday he will be featuring products available here now including OGIO and LEATT.  He will also have samples of Wolfman Luggage and the new Drift Camera. 

Patrick, from KTM, is our second guest talking about everything KTM.  The 2013 Power Wear collection, and full 2013 KTM lineup has arrived, and he will be able to guide you on what you need for a successful riding season.  Patrick will also be telling tales about his Dakar experience.

If you are interested in attending, or have any questions, email or give us a call 705-424-1515. 

Hope to see you then!

Mission Cycle

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Wednesday, 13 March 2013 14:20 Published in News


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