Gunbus 410 Cubic Inch V-Twin Motorcycle Completed

Gunbus 410 cubic inch motorcycle

The Gunbus 410 cubic inch V-Twin motorcycle is complete. The monster engine placed in a motorcycle frame of comparable size looked impossible and many who saw the photos were skeptical of the bike ever being finished but I guess, Clemens F. Leonhardt is one of those persistent guys who ignores the naysayers and keeps at his work.

The fuel injected, 45 degree 6728 cc / 410 cubic inch V-Twin runs through a 3 speed transmission with reverse and actually looks pretty good in its finished state compared to the initial photos, in fact, everything looks good. It puts out 523 foot pounds of torque. Seat height is 31.5 inches and overall length is 136 inches. It is a little heavy at 1433 pounds so high speed corner carving might be an issue and there aren't any photos of the big bike on the road so I guess we'll have to wait for the road test, that is if someone can actually road test this monster.

This is actually going to go into limited series production and a sidecar will be available as well which might help with balance when waiting at a light. I don't even want to think about a driveway tipover. I think this is great! Now, where's the video?

Thanks for the tip, Petr!

Lots of photos below:

Gunbus 410 cubic inch motorcycle

Gunbus 410 cubic inch motorcycle

Gunbus 410 cubic inch motorcycle

Gunbus 410 cubic inch motorcycle

Link: Leonhardt Manufacturing



  1. Zak says

    WOW. They REALLY need to add some covers for the primary drive and front sprocket or someone’s gonna get mangled

  2. kneeslider says

    “I love eccentric builds but why?”

    Because he wanted to, because he wondered if it would work, because he thought it was a neat idea, because he wanted to do something different, because he wanted to showcase his engineering skills, because he saw an engine and wondered “what if …,” because he would rather build something himself than watch someone else build something, …, the reasons are endless and every one is valid.

  3. says

    That is an attractive engine and the fit and finish appear to be of high quality.

    He could recoup money if this bike is marketed towards events like the monster truck series, among others. I don’t even know why I know about monster truck series….

  4. lostinoz says

    The girl in the pix is probably a pro model, those women are every bit of 5’10” on average… she looks like a midget on that bike!
    side car definatel would help, but I cant stop thinking of a trike it!
    Are those AIRPLANE tires???

  5. Paul Ventura says

    @ Zak:

    HAHAHA, maybe they should just change the name to the “Mangler 410”

  6. todd says

    pretty dang awesome. Look what he has to show for all the extra time on his hands. It’s better than a beer gut and couch potato butt.
    I couldn’t imagine trying to keep the thing balanced even while under way.
    Maybe Batman can buy it to scale down from his existing bike.


  7. chris says

    Put some hummer tires on it, and I bet the eco-friendly gov. Arnold Schwarzenegger would buy 5 of them.

  8. Old Will says

    Nice result of a concept. Scaling up the size of a motorcycle is unique. The taller riders will appreciate this. It got a little to heavy to be practical though. I’d still like to ride it.

  9. johnny says

    haha, this is so over the top, I love it! he deserves heaps of cred for pulling it off. Can’t wait for the video .

  10. says

    lostinoz: I believe Clemens’s original idea was indeed to use tires originally spec’d for a Boeing 767, although I think I also read somewhere that he ended up giving up on that idea because of issues getting wheels to fit, or because he couldn’t get the tread shoulders shaved down to a proper height, or something. I have no idea if the tires on there now are aircraft tires or not, but I’m pretty sure that was the original idea.


  11. aaron says

    so how would you turn the thing? if our model is indeed 5’10, she is leaned forward with her arms locked. with the bars mounted as they are, I’d assume the bars to be prone to “tiller” type steering (swinging left and right rather than pivoting one forward, one back)… ok, now try this out – lean forward, stick your arms straight out and try turning them about an imaginary pivot 4 feet away. it seems like I only have a few degrees lock-to-lock – anyone out there think otherwise, or feel you could conrtol a bike with this layout?

  12. Sean says

    I can’t help but feel that he shouldn’t have scaled the bike up, and instead given it a Hot Wheels, cartoony caricature feel. However, it’s one heck of an amazing build. I’d love to hear this thing at the drag strip.

  13. MotoWebbi says

    Maybe it needs one of those pulse-jet thingies bolted on the side of it to make it go properly?

  14. Azzy says

    There has to be a linkage there that makes steering feasible, something like a universal joint to turn that thing.

  15. pabsy says

    stunning, kudos to him

    whoever said trike, thats a great idea as sidecars are boring and 2 wheels isnt practical

    3 wheels would still look nuts and its something salable for shows etc, actually even for folks that just want one to ride, tour on etc

    anyways just stunning

  16. Alex says

    That is nice work , impractical and silly but I’ve never let that stop me before so I like it. The wheels look over size even for the size of that frame though. It is fun to play with the scale of things so even if it doesn’t really work as a bike it works as a way to throw your small/far away filter and most of us enjoy a little harmless trickery. What would be cool would be to turn the engine through 90deg. like a Guzzi. Now if we worry about where to put the petrol later could we mount that in a “normal bike frame” like a GS1000 or something with each cylinder coming up to allow you to burn your elbows on them during riding. The petrol can now go under the seat. I’m just stuck for a gearbox position.

  17. Walt says

    It weighs twice as much as the average v twin cruiser, but has four times the displacement and almost six times the torque of a Harley twin cam 96 (92 ft/lb according to Motorcyclist). By that measure the Gunbus is a relative featherweight. I always thought cruisers were overweight. Now I know.

  18. Wes Hill says

    My opinion: Possibly the dumbest thing I’ve ever seen in my life. Just because it can be done doesnt mean it should be….

  19. Seymour says

    That would be a really sweet bike if it was normal sized.

    Maybe the girl is really 3 feet tall but perfectly proportioned. Then I’d want the girl too. Just think how big you’d seem! But then you go and get on that big bike and now you seem small.

  20. Maxon475 says

    Whit that much torque i would like to see how holds up the chain.
    36 years ago I got one of the firsts HONDA 750 CB FOUR and man, didi I think It was huge .!Looks like a dwarf next to this . Impressive.

  21. says

    I think its a regular sized bike and he just figured out a way to shrink his girlfriend to make it look huge. An odd name, Gunbus, but a motorcycle but a pretty neat engineering exercise. And no, I don’t think I’ll be adding my name to the pre-order list.

  22. says

    I must say I always wondered what it would be like to supersize a bike and what it would feel like to drive it. Now I might even be able to do so.

  23. Rider1772 says

    Worth of praise this piece of craftwork, skills, imagination, hard work are easy to see …but honestly my first thought when I saw the article was..
    ..look what happens when your first girlfriend says ” size does matter” .

  24. James W says

    There was a day when an odd fellow named Henry Ford, made a very odd thing called an automobile.
    It’s certain it recieved a great deal of doubters then.
    Today, autos are a part of daily life;
    good to see someone take the path less taken.

  25. says

    Ah , Ok , it’s radical ,it’s cool . but is bigger always better ?
    I now the girls think so ,like the dream girl in the pix . but you can’t do it with that monster can you .
    But A for effort . now downsize to something driveable like boss hoss and you could probably find people who would like to own one .
    you’ll be richer for your efforts .
    Anyways enjoyed your build . I’d like to hear it running also …. and watch the smoke show !

  26. Tim Rauscher says

    Damn! he beat me to it! Let’s see it with a turbo and nitrous oxide injection….

  27. Devildog83 says

    I vote to call it “The Mangler” as stated above. This THING looks like a man-eater. The front sprocket is just begging to catch a pantleg or a boot strap, having the foot peg right next to it. Primary drive no better, like having a buzz-saw at your knees. How about balance? Yea, just try to stop it from crushing your leg when it catches a gust of wind at a stop light and falls over on you. You surely won’t be able to foot-check a 1400+ lb bike when you skid on that patch of gravel. I view this thing as an oddity no different to the giant drivable shopping cart, or the giant drivable Red Wagon… cool at first glimps, tiring after first minute. Why do people do this? Oh, because you can, that makes it relevant… NOT!

  28. Clevet3 says

    Devildog: you asked, “Why do people do this?” I refer you and all others wondering the same, to kneeslider’s response: “Because he wanted to, because he wondered if it would work, because he thought it was a neat idea, because he wanted to do something different, because he wanted to showcase his engineering skills, because he saw an engine and wondered “what if …” because he would rather build something himself than watch someone else build something, …, the reasons are endless and every one is valid.”


  29. rider1772 says

    To ” James W ” post #43 : I think you’re mistaken H.F with Herr.Benz, in some place (England?) his creation was deemed so dangerous that the law required a walking guy with a horn to announce the incoming “carriage”.
    My post (#42) means: This is rather for the Proof of Concept, Concept model, Kirsch Art section, like most of the beautiful chopper crafts, or my never patented high heel roller blades.
    About “Does size matter? visit this link of a guy who also successfully makes bikes:

    ..but they doesn’t even work!!

  30. mook says

    Mate AWESOME i want one,twice the weight of my Harley not a problem ill work it out,if you have what it take’s to build it[not many have]then i have the balls to ride it,give me a price im in,Mook

  31. says

    nice bike, have been riding for 45 years + and always worried about cars and trucks and so on, with this Mangler, it evens the match all right.
    Who’s scared of Freightliners now!!
    Ride on

  32. Mike Schneider says

    > Put some hummer tires on it, and I bet the eco-friendly
    > gov. Arnold Schwarzenegger would buy 5 of them.

    Arnold is the only man on earth strong enough to keep that monstrosity from crashing sideways onto the pavement two seconds after flipping up the stands.

    Jesse of “Monster Garage” has already built (in six days with helpers) a bigger hog with a Peterbilt semi engine:

    (The NOS kit is a nice touch.)

    Jesse at first wouldn’t take the advice of making it a three-wheeler….until he saw the gargantuan motor.

  33. vzryder says

    Testosterone wars. Boss Hoss and this thing. You shouldn’t need a crane to pick up your bike. Now you got something to jump monster trucks with. What will they come up with next? Too much time and loose change. I guess if you got it…….

  34. Doug R. says

    After long and thoughtful consideration, I believe I want one – no, make that two ; one solo, one with sidecar. Just beautiful, absolutely beautiful. Kudos to the creator!

  35. Johan says

    Dammmit. …. It was enivitable for some retards to come up with things like “stupid” “dumbest thing” etc.
    Im convinced that everyone who had a negative thing to say. . .

    a)Still lives with his/her parents
    b)Has no sustainable job
    c)Is “the dumbest thing”
    d)Is stupid
    e)Is married to “the dumbest thing” or “stupid” who probably weighs the same as the Gunbus
    f)Has never even ridden a bike
    g)All of the above

  36. Daren says

    Awesome! I’ll volunteer to drive it in a heart beat. I believe handling will not be a problem. Think about how a huge 200kg bike all of a suden becomes very stable once you get going above 10kph. Conversly a tiny 60kg scooter type thing always feels wobbly and unpredictable. My guess is that once it gets going it will be very stable. Stopping will be another issue. Cruising however will be awesome.

  37. jack says

    I love it! (why be normal) totally admire the creativity and the know how to make it all work! What’s next!! Jack W

  38. jonakajon says

    around 20 years ago a guy in Australia made a 5 litre v twin supercharged with nitrous oxide injection motorcycle. He made it from the middle two cylinders of a rolls royce merlin aircraft engine. the supercharger and nitrous kit were factory fitted to the motor when used as an airplane in ww2. 3 speed air assisted shift chain drive.
    He took it to the usa to compete in sled hauling comps at the bike shows but was banned cause he won em all

  39. says

    After a friend at work forwarded me an email about this I read through all the comments and noticed that only two people actually realized what they were looking at and what they were thinking. My response to the rest of you along with the designer/builder of this “Monstrosity” is “ARE YOU STONED?? Were you one of those little kids that stood at the window eating pant chips all the time? If you still don’t have any idea what I’m talking about drop the can of spray paint and Google the Phrase: (The Death of Common Sense) and have someone read it to you. Yes, if necessary have that person draw pictures for you. I’m thinking that this will be tested on the TV series “Testee’s” or the new series coming out called “1000 Ways to Kill Yourself”. Clemens F. Leonhardt, The next Howard Hughes?

  40. Jeremy Clark says

    That bike is so stupid, I LOVE IT!! Huge cudo’s for pulling that off. Let’s see the old ladies turn left in front of that beast! It needs a monster trike kit, and a train horn, and I’ll get another mortgage to buy one. Probably have to license it as a truck.

  41. says

    I beleive it is over the top but nice work . let me know if you need someone to give it a test run I’m open to any ride once just to say I did . keep it up!!!!!!!!!!!
    Ricky B

    P.S. as far as the girl gose I seem to get more miles out of the bikes

  42. Jerry says

    It looks to me he used aircraft cylinders then built the crankcase and crankshaft to match. Great idea.
    Many years ago I had the “what if idea” and built a sand buggy that had a Mercury outboard motor with a snowmobile torque converter with a homemade forward and reverse reduction gearbox. Ran it at Yuma, AZ sand dunes back in the early 70s.
    Jerry C

  43. says

    Wow twice the weight of my road king,and probably a smooth ride.Wonder how it corners in city driving(LMAO) although it would make a great highway cruiser.

  44. Harry says

    It’s unridable, a waste of time and money in my book. Just a big useless oddity. The design of the bike isn’t bad, but it should have been made smaller.

  45. will says

    thats gotta have balancer shafts coz that would jump off the ground if it didn’t. lol
    also who made the engine and tranny?

  46. Kenneth ferrer says

    To the person who built the bike. Are you the guy from Blastolene? They build practically oversized cars.

  47. Leo M. Mara says

    Wow! That’s great. I love this kind of vision and expression. When do we see and hear the video?

    I don’t care how tall she is. I’d like to see her in more appropriate attire, naked. Or are you worried she’ll distract from the bike?

    To answer the question “How do you get it off the center stand”, just kick it into gear and let her rip.

  48. Bulleteer says

    The thought of wanting to make something exclusive is fine; but something like this which is doomed to stay parked in a garage or w/e, is honestly, very sad. Common, this is a bike multiplied scale wise, obviously you can build one. But you need to perhaps multiply your physical dimensions in that ratio too, to ride the darn thing. As disappointed i’m to say this, but, WHAT A WASTE ! Poor Sod.

  49. MetalMicky says

    Maaaate awesom, right up my alley
    Give one to the crusty demons
    Ignore the hecklers they’re jelous

  50. MetalMicky says

    PS i think this is very ridable, just a matter of keeping power on and leaning it into the corners. Don’t see a problem so long as it’s balanced. (which i’m sure it is) :-)
    i’ll ride it just to prove it.

  51. Dave says

    I’m sure its rideable just like every other bike – counter-steering moves the tyre contact patch to one side of the centre of gravity and around it goes. No worries.
    But, stopping and not falling over is a whole new ball game where’s the retractable undercarriage. At least his gearbox runs at engine speed (to cope with the torque). Shame he didnt use a hydraulic drive – that WOULD be different infinitely variable ratios and and quite possibly no less efficient than a gearbox.

  52. Colin N Z says

    Awsome .But maybe unridable as noted.I have a partly completed road bike powered by a354 cu in Chrysler Hemi V8.Constructed by the late John Curtin who made Ford 390 V8 in Southwards Museum.I would be intrested in selling it if anyone would be intrested.The rego is on hold.Contact by Email.

  53. Bad Mr. Frosty says

    I am a little worried about the price for tires for this thing when they wear out, that is of course after riding it around with tow trucks on either side to help keep it upright. Maybe it would be best to let it sit in the living room.

  54. Rob S. says

    Myself I ride a Honda Rune it can be some what of a challenge to ride at times being that its in the big bike category but truly not as monstrous as the gunbus 410,WOW !This bike would be something I would like to take around the block. Rob S.

  55. Bridget says

    Damn! My man would look HOT on that bike! how much? and where can i buy one!?

  56. womble says

    i think it would have been a good trike build if one did have a whoppsee as a bike it would need a tow truck to stand it up again ( is that practical ) definatley needs to be a trike

  57. JStrouse05 says

    This is a great bike, for Shaq!!! If you’re not 6’8″+ 275+ this thing will crush you before you ever get if on the road, this thing is ridiculous!

  58. bobby smith says

    another article says that shaq IS the test rider, and also that the bike is made with gyros similar to the one’s used in segways but operates side to side rather than back to front.

  59. Chris says

    Honestly I think this was a great idea. There’s really tall people out there. Like me, I’m 7′ 4″

    Finally a bike that I could comfortably sit on, now I’m not that sure I could drive it, maybe if I built up a little more muscle I could.

  60. Joe Moore says

    The cylinders look like they are from a Wright-Cyclone 1820 Cubic.Inch nine cylinder radial aircraft engine. Aluminum Heads / Steel barrel. Gotta be a real thumper at Idle.
    A real challenge to stay upright at the stop light.

  61. Joe Moore says

    470 Cubic Inch aircraft engines burn 12 gallons per hour at cruise power settings.
    Estimate this monster would burn 8 -10 gallons/hour.

    Joe Moore

  62. Napewaste says

    Very nice. I have a mockup of something similar and is more efficient. Jay would like mine, too. It’s also an older design than this, so I thought about scaling up right at the first. Great minds think alike, and all that.

  63. says

    Jay Moore,
    As I work with radial aircraft engines, I too studied the pics. They are not Curtis Wright, (cast heads) or Pratt & Whitney. (forged heads w/ cut fins) They are probably German. The bore size 176 mm (6.929″) is not found in American radials.
    I applaud Herr Leonhardt for his vision and craftsmanship, although I have some critiques; aside from what has already been written.
    1) I do not see a starter and battery. This is major. Consider the forces involved on that aspect alone. If you can’t start it, you can’t ride it. It must be self contained.
    2) His website promises electronic fuel injection, yet I see no sensors, anywhere. Fuel injection is complex, the plumbing is bulky (especially for this volume demand), and has a lot of components that are difficult to hide. This is something I am currently dealing with for a client’s 142″ injected bike.
    3) The general layout. The bike does not have to be so big just because the engine is. Motorcycle chassis design these days include many proven concepts that are ignored here. For example, girder front ends were discontinued ages ago for good reason.

    All that being said, I would love to meet this man. I’m working on a 312 project myself.
    Jim Flower

  64. Jim Flower says

    Correction to above post: the bore size is 156mm, (6.142″) Not found in American radial engines that I am aware of. The fins closely resemble the Pratt & Whitney R2800 front cylinder head, an Alcoa forging with cut fins. However, the bore size is 5.750″, with a 6″ stroke.
    He’s got a cool engine. I would put it in a better chassis though
    (With a starter!).
    Jim Flower

  65. Robert Shonerd says

    The motorcycle is quite beautiful, although I don’t like the yellow color on the tires. I think it may need a sidecar for the potential rollover problems sitting at a light. Field of view in front is a problem. Only a very tall rider could see well enough. I could see this as a trike.

  66. Zlatzky says

    I was “lucky” enough to sit on this bike at the Motobeurs, in Utrecht, The Netherlands. I tell ya, i cannot imagine, how can somebody ride this beast. On a straight line, probably possible, but to steer… Nice to have one, but why? Impossible to use, and you need to build a triple garage to store the bike.

  67. tom neighbors says

    he built it becuse people say it cant be done and its stupid and its a wast of time and money . but i say good job man i would love to own it and hell yes i would ride it too just to prove to people i can lol any way cool bike man keep making things people say you cant. its fun to prove people wrong i do it all the time i have built several things that people said wouldnt work but you know what thay where wrong lol.

  68. brad says

    That thing is just about right!! 6′ 7″ i look like a monster on the Big dog and Boss hogg, this thing would work with a skinnyer front tire! Love it!.