Leonhardt 410 Cubic Inch V-Twin Motorcycle

Leonhardt 410 cubic inch V-Twin motorcycle

Leonhardt 410 cubic inch V-Twin motorcycleOver a year ago I pointed out a project over in Germany being built by Clemens F. Leonhardt. Clemens had some very big ideas but at the time all you could see were design drawings, and when you consider what this project is supposed to be, it's easy to dismiss it as a design that will never happen.

Well, checking back I see that progress is being made and as these photos show, it's big. In fact, until Clemens gets in the picture or another bike is next to it, you can't imagine how incredibly big this really is. Yow!

Especially in light of the Jesse James and JRL Cycles radial engine bikes, using the relatively small Rotec engine, the Leonhardt bike instead uses two cylinders from an old 9 cylinder radial aero engine, the very large variety, which gives you a 350 horsepower, fuel injected, 6728 cc / 410 cubic inch monster V-Twin. It has a 3 speed transmission with reverse. The motorcycle's overall length is 134 inches and weight is 870 pounds. Seat height is only 31.5 inches, pretty reasonable and lower than some production bikes out there. Speed will be electronically limited to 155 mph.

Original plans were for tires from a Boeing 767 but he's now found a supplier by the name of Rigdon willing to make custom tires in the appropriate size which are, you know, BIG!

The rolling chassis is shown here and this is not a one off custom. He plans to make a small number of these for customers and a sidecar version is planned, as well.

I really want to see this one when it finally gets on the road. He's working on another project, too, building a motorcycle around a Hatz single cylinder diesel engine which looks pretty cool. I like this guy's work.

UPDATE: It's complete!

Another photo and links below:

Leonhardt 410 cubic inch V-Twin motorcycle

Link: Clemens Leonhardt

Related: A Real Monster V-Twin
Related: 5000cc V-Twin by Lucky Keizer


  1. Sid says

    870 lbs. ? That’s crazy….not much more than a HD or a Kawi mega-crusier (relatively-speaking).

    NBA stars should take note

  2. 360Scott360 says

    How will this handle the ‘twisty bits’ compared to the ‘Wide Tire Bikes’….?

  3. Willie Schmitz says

    Wasn’t long ago I was wanting a bike that a 6’3″ rider would be comfortable on. Presto, here it is.
    Wonder what the tab in will be?

  4. John Bonanno says

    What’s the point? it won’t handle i’m not even sure it would be able to turn at speeds more than a crawl. I consider this a waste of engineering talent.

  5. sfan says

    Think of the gyroscopic forces those wheels & tires will create at high speed! Even with the length leverage from forks to grips (~3′), I am guessing some form of power steering will be needed just to start a lean. Note, it looks like four brake disks up front. Given the weight is no more than some cruisers, and given the size of the contact patch, that is a lot of stopping power.

  6. chris says

    air cooled boxer twins with funny front ends, autobahns, Nurburgring, and THIS?!?! what do they put in the water in der Deutschland?

  7. GenWaylaid says

    It’s like the mini-bike concept in reverse, isn’t it?

    What’s the sidecar? A Chevy Tahoe?

    It’s sad that Andre the Giant never lived to see this motorcycle.

  8. Skeeter says

    Please place this bike in the same category as underwater scuba-diving weddings with an Elvis impersonator.

  9. Rider1772 says

    “..Original plans were for tires from a Boeing 767..”
    “..two cylinders from an old 9 cylinder radial aero engine..”

    Hmm, Herr Clemens what about a C-130 with a loong forked front landing gear.. a F-16 with Corbin seat and pulled down handlebars..a Cessna 172 with kickstarter…

    Out of jokes Clemens, congrats and keep creating these amazing machines!

  10. Sean says

    Wow. I like. If the entire bike was scaled down, so that the engine became the main focal point and it looked slightly large instead of ever-so-slightly small like here, and perhaps if it was more like the Aussie one, then I’d like it more. Still… Rocketship. Rocketship.

  11. aaron says

    why does a 6.7 liter engine look puny and underpowed in this application? I’m ok with over-the-top crazyness, but without the rider to give a sense of scale this thing looks like a toy. it needs smaller tyres, or bigger engine…

    the line of sight for the rider spooks me, too…do you think he could see the brakelight of a rider if he was following close?

  12. Matt says

    I’m thinking that the detractors here may need some fiber in their diet. This thing is a piece of mechanical artwork, NOT a replacement for their crotch rockets. I love it! Keep dreaming BIG, Herr Leonhardt!!!

  13. joernson says

    I met Mr. Leonhardt about one week ago. And I took a seat on the GUNBUS. That is the second one. The first one had an automatic transmission and he went 200 km/h with it. C. F. Leonhardt is a calm straight old school engineer telling me that he never liked usual solutions. I found out I’m not alone in saying that a BossHoss is an ugly bike with its too small tires and no shape. Yes, it is a bigbike. I save my money…

  14. Jim says

    Are those the “Jugs” off of an R-1820? I missed the part on how he plans to start it. One kick-back would throw you over the moon!!!

  15. steve says

    I’m looking at the vehicle trying to find the transmission or method of power delivery to the rear wheel.
    Also any type of exhaust
    Smart and necessary is the extra disc brakes to tame the gyroscopic forces of those BIG wheels.

    Use of an established type of motor is a plus.

    Its difficult to picture trying to turn this beast at low speed, easy to see why it comes with a(n) (invisible) reverse gear.

    All in all, as an engineering idea, its great!
    You can just see Arnold with some 50 cal. in an action flick.

  16. bcubed says

    Yeah…the first thing I thought when I saw those tires was “WTF, did someone park their 747 in a bad part of town?” Actually, 870# ain’t bad considering about 200 of that is rubber.

    If I were to do it, I’d orient the crank front-to-back, using either a 90deg. V or horiz. layout. That way, the tank could be dropped and more realistic dimensions could be had. (But then it’d look less “like a Harley”…)

    Actually, I had the opposite thought: 8 Harley jugs in a radial as an engine option for experimental a/c pilots who love the “round engine” look. (I’m actually surprised he got 350hp, as I thought those radials redlined at 2500rpm.)

  17. Chuck says

    hacking up a beautiful radial engine to make that abortion of a bike….. is nothing short of criminal damage.

  18. rcdoug says

    This is the same as one that was built by an Austrailian back in the 70’s. That one was closer to real size and het nearly 200 mph. Woobly frame held it to that speed. This one looks basically worthless

  19. Shane says

    Ooooooooo Wahhhhhhhhhhhhhhhhhhh

    Uber cool and so totally gay!!!!!

    Now that is a real mans bike.

    It’s absolutely excellent.

    The ONLY donwside I can see with it is…. you could get between the cars in bumper to bumper traffic… cause it’s actually narrower than the rider…

    But a “turn on a dime” moped it aint….

    This is a really really cool looking bike.

    It’s funny tho, the really nasty “shit heapers” contributions, are done by people who are too stupid to try and too lazy to follow through…

    I’d love to have a ride of this…..


  20. franky j says

    The guys that would buy a bike like this would in all likelyhood be a lot tougher than those tatooed love boys of the Harley mindset.

  21. Cbraun says

    Is it done,would like to ride it but i know if that happens i would want to get one. thats means i have to sell my ktm 950 now

  22. says

    OK, so I’m a girl–I agree with Bryce (above) would love to see 7.6 liter, 350 HP monster out on the Bonneville Salt Flats–I wonder if you could launch it out to Snowbird ski area?
    Gotta love thos German engineers.

  23. says

    what an interesting artical to say the least. as a previous motorcycle shop owner and mechanic as well as a current rider, this really is the ultimate bike. it’s always nice to see someone thinking outside the box, that’s how new ideas evolve. larry wimmer

  24. Brian says

    WOW, what a vehicle, but I think it is almost in proportion, comparing motor to frame to foot/knee length.
    I see some people refering to an Austraian built bigbike, but does anyone have any references or links to that motorcycle?

  25. ++CHAMP++ says

    GREAT WORK !! Indeed it is …. but does it stand up 2 Y2K …. dat bike is THE most insane thing 2 evr b on road …. Y2K can put evn some of d monsterous supercars to shame …. LEONHARDT can only dream about achieving the levels of insanity Y2K did ….
    a helicopter engine inside a bike …. no mortal can evr achieve dose heights of craziness …

  26. Jorge says

    Alls I can say is WOW. Four-Ten cubies? Those Rigdon specials would definitely put the auties in check with the Knievels. The bones have to be strong to wear such big muscle. Stomping them down in mid-town would be a tragic ride indeed.

  27. Royce says

    Maybe you can offer a 1100 cc V/twin fitted as a spare. Just in case you get a flat tyre. And I hope it has air filters, otherwise you might suck in the odd pedestrian….Great work..

  28. John McClain says

    To all the naysayers, you aren’t builders and engineers. Projects like this are art, and art is done for its own sake. I’ve been building one similar for a couple years using cylinders off a Pratt and Whitney 1340, with five and three quarter inch bore and stroke. I’m still mocking my engine up, and this guy’s got his together. I only just saw it this morning, but I’ll bet my life it rides fine, handles like the builder expected, and will be around a long time.
    I’m also in the process of building a “round” engine bike as well, it’s another work of “art”, not a practical machine. Pushing the limits is how the limits are moved out. It’s imagination that brings things like this to life, that have been responsible for every bit of ease of life we live today, be grateful for those who have the courage to imagine the things everyone says “can’t be done”, they do it for you.
    I build old antique engines, new mundane ones, weird seldom seen before engines, and things that come out of my imagination. Doing anything less would be not fulfilling my potential. I’m sure the same goes for this guy, I just would like the opportunity to shake his hand, he’s another mind like Jesse James, and not related to the OCC crowd of billet barge builders.
    John McClain
    Vanceboro, NC

  29. tom says

    totally crazy,why?would anyone in their right mind,want something bike so big,might as well go out and buy a big suv…

  30. Bill says

    To SID: you beter take a look at that weight again!!! it wasnt 800+ pounds It was 800+ kilos. Thats roughly 1450 pounds. And to whomever commented “WHY”?

    We’d still be on horseback or walking if people like Henry Ford asked why.

  31. richard says

    First saw this on the front of Barnett’s mag. the pic with the girl sitting backwards on the bike. It looked like a joke. But no! It was real !!
    Jeez, I want one. But at a quarter of a million spondoolies it’s out of the reach of the average guy (maybe john travolta could afford one) and that’s a shame. I’d love to see a pack of these roll into town.
    Bravo Herr Leonhardt

  32. Kapil says

    Is it possible to have an output of 3000 cc, from one cylinder, of such size..????

    CAn there be any possibility..???

    Dnt think so….