The street-legal, single-cylinder KTM RC4 sportsbike

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To many of you, the bike you see here is something of a unicorn. A street-legal, single-cylinder sportsbike that weighs just 275lbs and makes 70bhp. That KTM LC4 motor is well-proven, has reasonable service intervals and won’t rattle your fillings out. Looks sexy in RC8-esque fairings too. The problem? KTM doesn’t actually make it, instead, the RC4 is only available in kit form from a German supplier.

Mid-capacity, single-cylinder sportsbikes hold so much promise because they’re: a) really light b) really torquey and c) incredibly simple. Those three attributes should equal accessible performance with the kind of handling typically reserved for GP bikes, all at reasonable cost.

Manufacturers don’t really make anything like this because its appeal is relatively limited to a few hardcore, small bike, track-riding aficionados. The modern 600cc, inline-four sportsbike sells in high enough volumes that its costs are massively offset by volume. You’re not riding a budget $10,000 vehicle, you’re riding something that’d give a multi-million dollar race car a run for its money both in performance and technology, just benefiting from the economies of scale. Engineering a bike like this RC4 from the ground-up would equal the cost of developing that 600, but couldn’t bring such high volumes, leading to a higher price. You may desire the more focussed, more special machine, more expensive machine, but the market at large wants that do-absolutely-everything, performance pinnacle 600 for less money.

But don’t lose all hope. Remember that future product plan for the Austrian company that leaked back in August? It included mention of a “Moto3 350.” Since that’s the wrong capacity for the class and it’s included on a list of production bikes, it sounds like KTM could be cooking up something similar to this RC4 itself, albeit even smaller and even lighter.

If it uses the same 350cc single as the KTM 350 EXC-F we’re currently tooling around on, then we’re pleased to report that that four-valve motor is an absolute peach. Smooth, powerful and quite unexpectedly torquey for such a small capacity. Fingers crossed.

In the meantime, you can convert your 690 Duke into an RC4 by writing the nice Germans at Mototech a check for €4,800, waiting for a box, then turning some wrenches in your garage. The kit alters suspension geometry, revises the ergonomics for sport riding (mirrored after the RC8) and fits that angular fairing.

  • quint7

    Like the Formula 450 bikes that were being pushed as an entry level ride for beginning racers. Airtech still has the bodywork available to convert motocross bikes and Racetech offers other goodies:

    • motoguru

      I thought about converting my 450 over at one point. I’d still love to.

      Either way, it’s still not a sick as balls looking trellis frame 690 awesome machine.

      I’ll take a fully faired CR500 while we’re at it too.

      • quint7

        I totally agree. This thing (KTM) is sick.

    • fasterfaster

      The challenge with those 450s is the maintenance intervals are brutal just for off-road racing. You start pinning ‘em down the straight of a road course, and they self-destruct, not to mention vibrate your wrists into seizures. The LC4, on the other hand, can actually handle it and is pretty smooth. This bike would be tons of fun. To put it in perspective, it’s got twice the power and 75lbs less weight than a Ninja 250 (plus real suspension and brakes) and those things RAIL at the track.

      • quint7

        Yeah I’ve never been a motocrosser but I agree, all of my buds that are bitch about maintenance costs. My answer to them…. learn how to turn a freakin wrench! (they all make way more than me so they reply “I pay people to do that”). I have heard that the LC4 is a solid engine and I love my ‘fat’ Hawk GT so I don’t doubt you on the 250 Kwaka.

        • Sean Smith

          Four-stroke MX bikes are insanely expensive to keep alive. Even if you spin your own wrenches, you still have to buy all the tools, gaskets, parts, and fluids, in addition to dedicating serious time and maintaining a workspace.

          • quint7

            With my buddies out there in the South Bay it is all about time. They make big cash and therefore their time is money. i on the other hand view that time wrenching as a way to unwind (til something goes wrong of course). I grew up in a ‘mechanical’ household so it’s just what ya do but for someone who has nothing more than a hammer, a flat tip screwdriver and some duct tape in the tool drawer of the kitchen it could be expensive just to buy in. But it’s pretty damn rewarding.

          • Gene

            But mechanicin’ is a BLAST! (and keeps me sane after sitting on my butt at the computer all day)

            But yeah, I’ve spent a ton for decent tools.

  • mugget

    Wow. You had me all excited thinking that KTM had come around… I remember reading a while ago about a race team that was running a bike like this, it seemed like a really good idea – lower running costs and a helluva good time. And not many people seem to think about this but from the looks of the photos I’d say the ‘crashability’ rates pretty high also. Ahwell, we’ll live in hope…

  • T Diver

    I think it looks amazing but I am probably missing something.

  • Ceolwulf




  • Johndo

    That bike looks awesome. If they make a nice looking naked version of this bike (better looking then the 690 Duke), same weight or less, at around the price of a Street Triple I’d be buying and I’m sure plenty others would be adding it to their xmas list. 275lbs and 70HP sounds like A LOT of fun…

  • 10/10ths

    For the love of God, build that sum’bitch!!!

  • filly-fuzz

    I am actually in danger of drowning in my own drool

  • Patrick from Astoria

    I would like to think that something like this would actually be pretty popular – and not nearly as expensive as a Supersport. The motor alone would be much less expensive to manufacture: one piston/connecting rod, one-quarter as many valves, only one cylinder to bore, etc., even with a balance shaft, plus the liberty to use less costly suspension pieces and so on.

    Seeing as how the major void in the market is still between the increasingly popular 250s and the 600s, there’s plenty of space for an elemental 400-500 Single – flyscreen or half fairing, single disc front – for maybe, what, realistically $6-7000? Maybe not an overnight success, but definitely a serious contender for a sustaining sales level once word gets out.

    • Mr.Paynter

      The gap is being taken up, Kahasaki has the ER-4′s, although I’ve yet to see them in the flesh!

      • Wes Siler

        Those are just sleeved 650s. No weight or cost benefit.

        • Johndo

          The 400 does take 0.5L less fuel per 100km (4.8L/100km), also I know in Canada license plates are less expensive on bikes that are 400cc and less. (in Quebec for example licenses cost 633$/year for the 650 and the 400 cost 377$/year. Otherwise they are pretty identical..and here the 400 is 1200$ less then the 650 (which is still strange considering 98% of the bike is identical…) but the real cost benefit is overall running costs :)

        • Mr.Paynter

          Hmm, I didn’t know that, wonder if there’ll be a valid price-difference then and whether you could unsleeve them? I’ve heard we may be seeing these next year and I have an

          I hate that here in South Africa I pay the same for my bike’s annual licence as anyone would for a small car (ie my moms’ Toyota Tazz 1.3l)BUT then I see how much you guys pay and chuckle, my US$20 a year seems pretty decent.

  • Ben

    Classic example of a single cylinder sport(ish) bike was the SR500. It cost more than many multi cylinder bikes of the era, was a wierd fringe product and not very many sold (in north america). Man oh man is that little thumper a riot to ride though.

    its hard to sell “fun” over the better bench racing stats and cheaper price of a more plain bike but if anyone is going to do it its KTM

    • Mr.Paynter

      +1, I borrowed a mates’ SR500 the other day expecting a bigger brother to my SR 250 and I was blown away, lound and fun and not so fast I end up in jail.

    • michael uhlarik

      Some perspective.

      The SR500 was one of the most successful motorcycles aver produced. Yamaha manufactured it, and its derivatives for twenty years in Europe, Japan, and all across Asia and Latin America. That motor, lifted from the legendary XT500 (the world’s first adventure motorcycle), was one of the most advanced singles around, yet it was able to withstand extreme abuse and cheap to make and run.

      The SR family grew, and inspired dozens of copies from Honda, Suzuki and Kawasaki, and to some extent was the template for many of the current big Chinese brands when they began developing their first four stroke bikes.

      Today the SR is a cult classic among young cafe racers and custom shops in Japan, where the 400 was made up until the late 1990′s. The design concept of the SR was the direct inspiration for the MT-03.

      • Mr.Paynter

        Thanks Man! Some cool knowledge!

        It sucks they’re disappearing so fast out here in South Africa, they’re like hens’ teeth!

    • pplassm

      I’ve got 2 in my garage. And 1.5 XT500′s as well.

    • NoVeloNoVin

      Kudos to HFL for bringing this tantalizing bike to its readers’ attention. At 275 lbs and 70 bhp — presumably at the crankshaft — this bike would spank my SRX-6 — 370 lbs and 41.5 bhp at the rear-wheel. In the hands of a suitably skilled rider, the KTM would doubtless out-handle the SRX as well — 25 years of frame and suspension progress and all.

      That said, as a street single, the SRX proved to be even less popular than its cousin SR500, and it was imported to the U.S. only for the 1986 model year. Because no one who was in the market for a 600 street machine at the time understood the bike, it was possible to buy a new SRX as late as 1988 or 1989.

      BUT, I sense from the comments here that the climate has changed. If this bike were brought to the United States, I expect it would be a resounding success. If nothing else, its availability would break the monotonous either/or of supersports on the one hand — which very few riders can exploit to full effect — and the paleolithic American cruisers that run mainly on image and marketing on the other. (Disclaimer: I currently ride a tube-framed Buell. Crude, but great fun, and already more bike than I need.)

      In any event, it is encouraging encouraging for me, at 52, to see a younger generation of sport riders interested in street singles, especially when some of those younger riders (such as HFL’s publishers) are skilled enough to use modern liter bikes near their limits. Bigger isn’t always better.

      As has been said here many times, the U.S. motorcycle market needs greater variety, more genuine choices. This bike, or KTM’s factory equivalent, could be the fuse that sets off the fireworks.

      • michael uhlarik

        Ah, I forgot the SRX. A student of mine had one in Barcelona, and it was a sweet ride. That 500cc single produced so many heirs, both upsized and downsized, and had a profound influence on the entire thumper market.

        The Kawi KLX/KLR, Suzuki Big, and of course Honda’s Dominator all owe a lot to the success of the air-cooled, remote sump Yamaha single. The XT600 was being punched out in Italy and south Asia long after its demise in the US. You’ll be happy to know that the SRX was a very big deal in Japan and Europe.

      • DoctorNine

        I understood. I still miss my SRX-6. Rode that thing across the continent too…

  • Scott-jay

    Is KTM & it aftermarket making some neat-o bikes, or is HFL warping my perspective?

  • rndholesqpeg

    The 690RC4 bike would be a great bike to try and dominate some SV’s in a light-twins class.

    But for an awesome single cylinder race bike, this guy’s 848 that had a cylinder lopped off is a great take on a modern SuperMono:

  • Miles Prower [690 Duke, MTS 1200]

    Ever since I saw the first photos of the RC8 concept model years ago, I’ve been a huge fan of what I think is still the best-looking sport bike by far. But I always feared the RC8 would be too much sport bike for me — so I never thought to buy one.

    But an LC4 based “RC4″? Wow, I’d definitely consider buying one if KTM made it.

    The kit bike here? Well, it looks pretty damn cool! If I had a spare 690 Duke, $6200 hidden underneath the mattress, and a couple weeks of free time, I would consider taking the plunge.

    BTW, it’s funny to see the original parts redressed a bit on the kit bike. The stock tail is there — with the holes for the license-plate holder and turn-signal wires out in the open. The projector-lamp headlight assembly has been moved off of the fork tubes and into the fairing. Etc.

  • R.Sallee (Ninja 250)

    I have no desire to ride a full-on sport bike.

    Except this. I want this.

  • smoke4ndmears

    SV650 HP with nearly 100lbs less weight. Please, do make!

    • Devin

      Wow. That really puts it into perspective.

  • TilJ

    Wow. I agree with filly-fuzz. I’ve already read this article about a dozen times. The bike and concept started out eye-grabbing and grows more enticing the more I think about it. Reminds me of when I first read the Supermono article in CW back in the early 90s — I still have that magazine stashed away.

  • the_doctor

    For the cost of the bike plus the kit, you could have something really freaking cool. I think it is a pretty sweet deal.

  • Jesse

    I’ve devolved to incoherent grunting and making grabby-hands again.

  • Brammofan

    Looks like someone just posted the whole article on reddit. Call the copyright police.

    • Roman

      I have friends who constantly link to HFL, yet complain about the $1.99 fee every time they do it. That pretty much sums up the internet for me….

    • Brammofan

      It’s gone – deleted – now. I’m imagining myself, as drawn by Frank Frazetta, atop a small hill, holding a flag with a copyright symbol on it. Even if it’s not true that I had a hand in this, let me dream.

      • JVictor75

        Would you be wearing the Death Dealer helmet too? Stylized hordes of demon lawyers baying at your feet awaiting release? Hmmm?

  • Miles Prower [690 Duke, MTS 1200]

    Here’s a new KTM 690 Duke on eBay for $7k. I paid just over $10k for mine two summers ago.

  • Dean

    Oh, I so wish this (or something similar) would go into production.

  • Slothrop

    I asked Mototech via email about the kit. They replied that they don’t ship it; they do the conversions at their shop. So now I’m gutted. I was seriously close to pulling the trigger on this. I’d so love to have a lightweight sportsbike that doesn’t need to be revved to 15k.

    • nbeato

      The coldest of wet towels

    • kat

      that is so depressing. :( i guess i’d have to move to germany to get one. not likely. bastards.

    • Slothrop

      An update: I sent another email to Mototech and got a different reply this time. They say that they CAN ship the RC4 kit to the states. Now I’m all jonesing again… Probably be around $15k all told, which is steep, but wow what a bike.