Radial Engine Powered Motorcycle

Radial engine powered motorcycle

One of our readers sent us this photo of a motorcycle powered by a 7 cylinder radial engine! We have no details of where this is from or who built it. If any of you have seen this or know more about it, please let us know. Several motorcycle builders, including Confederate, say they are using a radial engine when what they have is simply a two cylinder slice. This bike uses the whole thing! Incredible.

More info: The engine seems to be a 110hp 7 cylinder radial from Rotec Engineering. Rotec is an Australian company (Why am I not surprised when I think some Aussie did this?)

Update: Maybe not an Aussie. Maybe Jesse James. The bike was on display at the Legend of the Motorcycle: Concours d'Elegance in California this past weekend.

Update 2: A commentor below was actually the photographer for this first photo and confirms the builder as Jesse James. Photo by Neil McFarland of Santa Cruz, CA. Nice shot, Neil! He has a link in his comment to more photos.

More Photos Below:

Followed an incoming link back to the Speedzilla discussion board and found two more photos. As one commentor below indicates, he believes this is a Jesse James creation and looking at the Maltese cross on the headstock, he may be right.

Radial engine powered motorcycle

Radial engine powered motorcycle

Big Thanks, Jeff, for the original tip.

Link: Rotec Engineering

Here's the fellow that modified the engine for this motorcycle:
The Kneeslider: Radial Motorcycle Engine Modifications

The Kneeslider: Radial Engine Motorcycle by JRL Cycles
The Kneeslider: Radial Engine Motorcycle #2
The Kneeslider: Legend of the Motorcycle: Concours d'Elegance


  1. mark says

    Damn, they stole my idea! I’ve been wanting to build one for a while but don’t have the funds (those engines cost a fortune!). That Rotec engine is even the one I had my eyes on.

    My bike would look a lot better though — less cruiser and more cafe racer-styled, with polished aluminum bodywork to give more of an aircraft engine cowl effect.

  2. kneeslider says

    Coffman starters, … very cool. Remember “Flight of the Phoenix?” Only one cartridge left …

  3. Travis says

    I read that it is a Jesse James built bike over on Adventure Rider. One of the members was there(at the Concours this past weekend, and seemingly where you got the photo), took a gazillion photos and talked to a lot of people.

  4. JoeKing says

    Wouldn’t it be really cool if they mounted the propeller & let it run like an airplane???

  5. kneeslider says

    Thanks for the ID on the picture. I looked through your album, great photos of the radial but also of all of the other bikes. What a lineup! Makes me wish I had taken the trip over there.

    Amazing as the radial is, there were other bikes there I would have spent more time looking over.

    Thanks for the great photos.

  6. Jack Tar says

    For an old Navy, and former Round Motor Mechanic, this idea is simply mind boggling… I’d say operating this thing absolutely needs long arms, stubby legs and an asbestos suit!!

  7. Harry says

    The Jesse James incarnation won’t run because the sidedraft Bing carburetor is presently mounted as an updraft carburetor…

  8. P. W. Elliott says

    Reminds me of a couple of photos in the old “Autoweek & Competition Press” from the ’60’s – both a wheelchair and a go-cart with small-block V-8’s installed. Someone said they didn’t build them to run but just to roll out and listen to the comments.

  9. Bob says

    I flew radial engine Attack bombers in the Navy. I had a big right leg due to the torque on takeoff. IMHO, mounting the engine with the crank fore and aft is likely to wind up with the engine laying on the rider’s left knee with a good application of power.

  10. says

    I have a suspicion that the silver bike on this site — radial engine mounted cross-wise — will not operate. Obviously, someone may be proving me wrong already. But I believe the rotational torque of the engine under power will cause the bike to tumble sideways, where as the in-line mounted radial could operate, the torque being in the same plane as the forward motion of the bike.
    My suspicion comes from the internal mechanics of a radial engine — one large con rod “throw” (journal) onto the perimeter of which the other six (in a 7-cyl design) normal sized con rods attach and move in a toggling fashion. The rotational inertia on the master journal and the crank is huge, and might make the bike inoperable in a cross-mounted design. — Just my guess.

  11. flatwins says

    Not to mention that the gas tank looks like it holds enough fuel to get down the street and back.

  12. Andrew Stanford says

    Jesse isn’t big on building things that DON’T run.. lol… as a matter of fact, he’ll blow’em up if they just don’t run “right”….

    As far as the torque, it does seem that way, but, don’t forget V-8’s have a lot of rotational torque also, and they have been putting them in bikes for years. I have seen lots of “Boss Hoss” V-8 bikes, even with big blocks in them.

    From talking to a few owners, they tell me that if you rev them up quickly, with the clutch in, you definitely feel the torque, but as soon as you let the clutch out, you don’t. Not sure why, as I am not a physicist, but I have had them blow be me like I was sitting still, full screaming throttle, and they don’t look unstable at all.

    From my limited physics knowledge, (very limited, I agree..) I wouldn’t think that the arrangement of the cylinders would have any effect on the torque produced. I mean, the crankshaft is still going around, therefore the torque is still present, no matter where the cylinders are located, and the torque the crankshaft is putting out would be the same.

    Now, if you wanted some REAL fun…. try mounting a radial engine of the design where crankshaft is static, and the cylinders and propeller turn together…… that would be…. um…. insane… HA!

  13. Andrew Stanford says

    wow, I wish I could EDIT my posts… “rotational torque” uh… yeah… as opposed to what OTHER kind of torque.. .oh well….. no edit for me.

  14. Jeff Scott says

    I also believe that the torgue from the cross-mounted engine would make the bike very unstable under acceleration.

  15. gino falcone says

    I saw this in the japanese VIBES mag! what a MONSTER! i had my wife read it to me and it says Jesse built it. Its Blue and has the West Coast Chopper emblem on it its fantastic! a real work of ART…

  16. Dick Vennerbeck says

    The bike was built by Jesse James in his custom shop adjacent to the West Coast Chopper facility. I have a photo of it during it’s construction. I’ll be glad to send it if you give me an address. Dick Vennerbeck

  17. Ron says

    I have a picture of this bike before painting in Jesses shop parked next to his custom Hummer. Like old harleys, it had rags under the radial due to oil leaks.

  18. FRE says

    Having the engine cross mounted should not be a problem. The Honda GoldWing, the Honda ST1300, BMWs with opposed 2 cylinder engines, and the Motoguzi have cross mounted engines and it’s not a problem for them. Granted that if you were sanding still and revved the engine quickly in neutral on any of those bikes, the bike would tend to rock to the side a bit, but not enough to cause problems.

    One of the problems for the bike with a radial engine would be ground clearance. You can see that one of the cylinder valve covers is almost touching the ground when there isn’t even a rider on the bike. With even a very slight lean angle, other valve covers would touch the ground. Obviously it isn’t very practical.

  19. says

    wow, i cant believe how many peoeple say bad things about this bike. this thing is freakin awesome. even if it never “drives” it is something really trick to look at. awesome piece of art

  20. Bob says

    Uh….If you said a moto guzzi didn’t transmit the torque while riding, you never rode one. The one I rode wanted to fall into or straighten up out of the corners- depending on how much gas you gave, and what direction the turn was. Takes some getting used to!
    I imagine some of the bikes that run longitudinally have counter balance shafts.
    What I’d like to build is a go kart with the small jet engine from a missle I saw at the pax river museum! 600 lb of thrust in a package about the size of a 5 gallon bucket.

  21. Wild Bill says

    ugh!!, think of the heat that big motor gonna develop….be like riding into a the exhaust of a 747….lol

  22. Michael says

    About the physics of torque and this awesome build. Torque is only measured (and felt) when resistance is present. I have no doubt that the engine runs just fine. It’s all a matter of controlling that power when the transmission is in gear and the rear wheel is providing resistance. If done carefully, I’m sure that it can be controlled.

  23. Phil Marks says

    Response to Andrew Stanford’s notes dated Jan24:
    Static crank/rotating cylinders/radial configuration – it’s all been done and I’m not talkin’ about Sopwith Camels! Go looking for information about Megola motorcycles, made (I think) in France around early ’20s. To top it all off, they were front wheel drive. No clutch, you paddle off by foot to start the engine and one gear is all you get. Very crazy, very cool.

  24. Don says

    Wouldn’t you like to see Jesse James ride the thing from California to Sturgis? When he got there he would look like a hot dog roasted on someone’s grill. That’s one weener roast that Sandra wouldn’t like!

  25. Chuck Kottke says

    Hmmm… It certainly adds a new dimension to the phrase “flying down the road”! 😉 Is it comfortable to ride on, or does the shape give the ‘pilot’ back trouble??

  26. Grant says

    This one IS a Jesse James creation. I saw it in one of the mags a few months ago. There is a similar radial engine bike that was also written up a bike mag in the past few months but I lost the mag and can’t remember the builder.

  27. David Gibson says

    A VERY pretty engine. Interesting that power is taken off the ancilliaries-end of the unit and that the timing-gear end is blanked off. Maybe the engine cools better from the front.

    One could achieve better ground-clearance and lower centre of gravity if a “corncob” radial was used. ie Multiple rows of cylinders with reduced radius. Same engine capacity could be achieved, smoother power delivey guaranteed.

    As for the torque effect, a lot of perceved torque (and gyroscopic effect) in an aircraft comes from the propellers much greater radius than the various whirling bits inside the motor. In this application it could be reduced or eliminated with a counter-rotating flywheel. Look at helicopters with two rotors on a common axis. They still have only one engine turning in one direction but the two rotors of equal inertia and aerodynamic performance, turning in opposite directions to each other, cancel ALL torque effects so that the small tail rotor is no longer required.

    Fantastic site!

  28. Harold Dixon says

    I wonder how he got it to stop leaking oil? Any radial mechanic knows that if it aint leaking, its out of oil. A 4360 Corn Cob radial would be awesome. No matter what, this bike is very smooth and clean. As for the torque, without a prop and it small engine size it wouldnt be that bad, not like a Pratt Whitney 2800, 3350, or the 4360.

  29. says

    Interestingly, this is the second Rotec powered chopper I have seen on the web. The other one appeared on Rotec’s own stand at Oshkosh 2006. Oshkosh is the world’s biggest experimental plane show and thousands of people would have seen the chopper there. To my mind, it looked better than this one because the engine was not set accross the frame, it was 90 degrees different. Therefore those beautiful alloy cylinder heads would not have been threatened if you leant it over a bit too far in the corners. You can see it at
    It was built by an American firm, JRL. You can also see more photos of it in the Oshkosh 2006 section of the Rotec website. Have a look, it’s awesome.
    Mike Holgate, UK.

  30. Peter Hansen says

    According to local experts the radial engine is an Alligator from an amphibious tank from the sixties, I just mounted a motor like it on a stand for display, brand new never started, but sitting outside for years, what a shame.

  31. SUPER KONG says

    The Seven cylinder radial engine bike was not made by an Australian. It was made by an American, Jesse James from West Coast Choppers. A little bit of a clue for you would have been to look at the Iron Cross logo of west coast choppers on the front of the bike in gold. That and the red bike next to it is another west coast choppers bike The El Diablo 2.

  32. bob says

    Is there anywhere on the internet where we can see and hear this beauty running? What a masterpiece!

  33. Dean Siders says

    Jay leno should have one of these.
    I love odd ball and new creations.
    this one is great!

  34. Jimmha says

    Meh – Get back to me when he builds one with a Wright R-3350.

    The R-3350 Duplex-Cyclone was one of the most powerful radial aircraft engines produced in the United States. It was a twin row, supercharged, air-cooled, radial engine with 18 cylinders. Power ranged from 2,200 to over 3,700 hp.

    As my old Chief ADR (Aviation engine mechanic, reciprocating) used to say, “The C-121 Connie was 144 sparkplugs flying in close formation.”

  35. David says

    Just cam across this thread for the first time, and noticed the chatter about torque (rotational and otherwise?). Anyone familiar with aircraft applications is quite aware of the torque problem (I’ve heard you could tip a P51 Mustang onto its wing tip if you wound it up to fast). One thing an airplane has, and a motorcycle doesn’t, is a HUGE propeller, and its wind resistance. This would absolutley dwarf the rotational inertia of the crank shaft.

  36. Oz says

    there is an el diablo 2 next to it…its a west coast chopper……..they even have this one on the website now

  37. rob says

    i have to say i dont think this is a jesse james….as his company is Westcoast Choppers yet the seat you can clearly see B T W even tho you noted the siting of the Maltese Cross almost always somewere on te bike its tagged with the westcoast choppers logo other than in a place that would be ard to notice unless you carefully inspect the bike

  38. Rob C says

    I can’t believe some of you guys! This one below in particular; One of the problems for the bike with a radial engine would be ground clearance. You can see that one of the cylinder valve covers is almost touching the ground when there isn’t even a rider on the bike. With even a very slight lean angle, other valve covers would touch the ground. Obviously it isn’t very practical.>>>>>SO WHAT!!! I really doubt Jessie or anyone else would consider this pratical! Is a chopper practical? Some things are done just to do them! If you don’t understand that, I almost feel sorry for you! How about the V10 motorcycle Chrysler built, was it practical? It’s called FUN!!!!!!!

  39. Shawn says

    I have a pic of a bike with airplane engine would like more info on it. and how to post it on here??

  40. Chris says

    Reading through this and similar threads it amazes me the coments people write, fuel tank size, ground clearance, where would you put your shopping, what wrong with this world? have we all become so sanitised that ideas and new approaches and anything pertaining to ‘fun’ have to fit into some pre-defined law on obscurity. THE BIKES COOL! LOOK AT IT! I love the fact that we live in a world where this thing can exist and I personaly wouldn’t care if someone once saw they had a wrag under it because it drips oil, when you park, put a wrag under it. It’s an engine it moves and is full of oil…

    Lets all conform like little automitons……. Line up everybody….

    It’s a cool bike, alright, look at it…

  41. Erik Cantu says

    Great bike, but 110 HP??? Maybe out of two of the seven cylinders…Methinks Rotec is being a little humble about their engine’s specs.

  42. Neil says

    Great custom bike and engineering exercise.
    Your physics is completely correct. It would make absolutely no difference how the cylinders are arranged to the force of the torque reaction. Only how fast a given rotational mass is accelerated will effect it.
    I’ve been riding 36 years owned a 1000c Guzzi, an 850cc Guzzi and a couple of old BMW 800cc (also numerous Japanese single twins and multis, and several British singles and twins) been a professional rider, didn’t have a car licence until I was 30 and Bob I have to say I never, ever, ever experienced any torque reaction whilst moving on a Guzzi (over 200,000 miles on Guzzis) this includes making both the bike wheels leave the ground over jumps and humpback bridges, ever! ever! (or on Bee ems)
    (there are two gyroscopic stabilizers (front and rear) on every motor Bi cycle that prevent (longitudinal axis) torque reaction whilst moving.)