Allen Millyard Builds a 5 Liter V-Twin

Allen Millyard 5 liter V-Twin out of two cylinders from a Pratt and Whitney 1340 radial

Allen Millyard 5 liter V-Twin out of two cylinders from a Pratt and Whitney 1340 radial

Wooden patterns for casting the crankcase

Wooden patterns for casting the crankcase

Allen Millyard, everyone's favorite Dr. Enginestein, has done it again, this time taking two cylinders from a Pratt and Whitney 1340 radial and making himself a 5 liter V-Twin, the "Flying Millyard."

Everything is hand made, including the crankshaft and connecting rods, then, in what seems to be the new popular skill among high level engine builders, he created some wooden patterns and cast an aluminum crankcase for the beast.

The engine runs a dry sump with twin pumps, twin SU carbs, points ignition with manual advance / retard and twin plugs per head.

Allen Millyard 5 liter V-Twin out of two cylinders from a Pratt and Whitney 1340 radial

Allen Millyard 5 liter V-Twin out of two cylinders from a Pratt and Whitney 1340 radial

The original P&W 1340 radial was a nine cylinder, 1,344 cubic inch, 22 liter engine. The new 5 liter engine is intended for a Flying Merkel type board track racer, a BIG board track racer I imagine. This should impress the boys down at the Ace Cafe, don't you think?

Video below:


  1. starmag says

    Certainly,Allan Milyard is a god, if not the. v-12 kz2300, v-8 Z1, viper bike, 5 cylinder Kawasaki two strokes, mountain bicycles,etc. This should even make the Harley guys happy. He’s easily the coolest builder. Always great to see something new from him.

    • Woodco100 says

      There is only one God and it certainly is not this gentleman.
      Despite his many earthly talents.

      • Nicolas says

        after politics, religion … wow.
        I believe this was a 2nd degree term, an expression. Some folks need to chill and/or get some sense of humor.
        Let’s talk bikes

        • Hank says

          especially since it was probably a play off of “Dr. Enginestein”…..

          “it’s aah-LIVE! IT’s ALIVE!!!!!”

        • starmag says

          Hank, actually a riff off of the “Clapton is God ” London graffitti of the ’60’s.

      • Eric Kent says

        It seems that 99.999% of the people understood his comment to be a huge exaggeration and not meant seriously he just meant he has huge skills. Why didn’t you get it? Oh you get off on being in the high seat pointing your finger and saying AND HE SHALL GO TO HELL FOR THAT and stuff i get it well . Good for you I think my bike needs me now. Bye Bye

      • Lance says

        Actually Wood, there is no god. Allan Milyard is the closest thing to god we have on this earth. Well, him and Snoop Dogg…and chuck norris.

        • Al says

          Allan Milyard may have some competition.

          two cylinders cut from a Rolls Royce Merlin (from a DeHaviland Mosquito) making a V-twin 5 litre, shoe-horned into a bike frame, with a supercharger and a Nitrous Kit (the photo is an early one before the blower was fitted into a cut-out section from the fuel tank). Australian “Lucky Kaiser” is the man’s name and he used to take it to bike shows and start it up. Loud!

  2. Paul Crowe says

    These cylinders from the old P&W radials are beautiful with the way the fins are cast into the heads, but it’s those very cooling fins that make this engine even more suited to mounting it with the crank in a longitudinal orientation, like a Moto Guzzi or up front in a Morgan 3 wheeler. That way the wind flows over those fins properly and wouldn’t that make for an imposing appearance?

    • starmag says

      Paul, no question about the cooling, and it would look great Moto Guzzi fashion, but the torque reaction sideways in the frame might make it completely un-rideable. I cant wait to see the finished bike and how he deals with all that low rpm torque. It seems too big to put in a human-sized bike, but I would have said the same thing about his Viper bike and he made that work, although with it’s riding position I don’t think I’d want to tour on it. Is there some contest I don’t know about where the grand prize is knocking back pints with Allen in his garage/shop? I’d like to enter.

      • todd says

        no problem, a typical bicycle frame can easily handle a couple hundred foot-pounds of torque. Power, on the other hand…


      • tim says

        People ride those Boss Hoss abominations and they’d have as much torque as this or more. Sure you would need to be careful…. but you’re riding a 5000cc V Twin. You’re going to be careful.

      • GenWaylaid says

        I recall a diesel engine for motorcycles that was showcased on this site which used two crankshafts, counter-rotating and geared together, to resolve some balance/vibration issues:

        So if one is already making cranks, cases, and cams for this engine, why not attach the second cylinder to a second crankshaft, rotating in the opposite direction? Some balancing would be taken care of by symmetry, too, as in the diesel design. There’s still a lot of mass moving up and down, though, perhaps enough to really shake the front end of a 3-wheeler at idle.

    • Domenique Hawkins says

      Yes, a Morgan 3 with a 5 or 6 speed trans would be a real gonzo ! A real muscle trike.

  3. Tin Man 2 says

    Guys cut off the Fenders add low bars and claim they built a bike. Now this Craftsman BUILDS a bike, Fantastic.

  4. r4990 says

    Be nice to see it beside a “normal” V-twin just for scale. I think it is MUCH bigger than it looks standing all alone like that.

  5. Tanshanomi says

    I agree. And the fact that he does all that with simple, understandable tools and techniques just heightens my respect for him. There should be a bronze statue of Millyard erected in some city center and songs sung of him by future generations.

  6. Hooligan says

    Dunno about the boys down the Ace but I’m sure his neighbours were not that impressed.
    Absolutely beautiful cylinder heads.

  7. JasonB says

    Awesome. But I have a difficult time seeing an engine of this size and proportions in a “Flying Merkel type board track racer”. Those were esentially bicycle frames with engines- this monster motor took four men to carry!

    • Paul Crowe says

      I had the same thought. Millyard refers to his intended build as a 30s Flying Merkel “board racer” and in another spot as a “sand racer.” I guess we’ll have to wait and see what emerges from his mind as he starts building it, but it will be on a somewhat larger scale than usual, no matter what it turns out to be.

      • Tirapop says

        Google Glenn Curtiss V8. The aviation pioneer built a speed record bike with a huge V8 motor he designed. It’s from the same era of the Flying Merkel. I don’t know if the V8 did double duty in any of his airplanes to make the airplane-motorcycle connection more apt.

    • Paulinator says

      I saw one of Glenn Curtis’ early v-8s at the Canadian Aviation Museum in Ottawa a few months back. It was much smaller than I had envisioned it to be. I remember reading that Glenn Curtis started manufacturing engines with a drill-press and a lathe, as did some other famous flyers of the period. The early engine technology always amazes me.

    • Scotduke says

      I’ve seen the Curtiss bike in the Smithsonian. It’s worth noting too that the bevel drive isn’t encased and I don’t think it was when it was built, so after the first few seconds it would’ve spun off any lubrication and been running dry. It also has no brake, other than a crude pivot lever that rubs against the tyre tread. The spindly bicycle frame the engine is in has no suspension at the rear and not very rigid bicycle type forks.

      Curtiss had a lot of guts to ride that bike at the speed he did. Either that or he was nuts, or maybe some kind of combination of both.

      • Paulinator says

        I’ll be up in Washington next week. Won’t have time to get to the Smithsonian, though. Damn. Those early pioneers had special seats made to accommodate their (ehem) fearlessness.

            • starmag says

              I should have said” street legal air-cooled V-8 as installed in a working motorcycle”. Not a car or builder motor only. Curtiss and Millyard are the only two I can find and Curtiss’s bike was not street legal, Millyard’s Z-1 is.

  8. '37 Indian says

    As a retired aircraft mechanic and still avid motorcycle owner/rider/ restorer/collector, I’ve imagined doing this very build, although I may have used the smaller 985 top end. Interesting that someone actually did it. Not just the P&W, lots of radial engine heads are works of art. What you don’t see is that all of the rocker arms, cam followers, etc, are in ball or needle roller bearings. In a round , multi-cylinder configuration, they run pretty smooth, but in a v-twin design, with 150 cubic inches per explosion and no balance shaft(s), I can’t imagine riding this in a motorcycle. Just think what a Harley Sportster would vibrate like at 4 times the displacement!

  9. Paulinator says

    I made the call once, to an aero-engine rebuilder in NY state that specialized in big radials. I left a message asking if they had a usable pair of jugs and pistons that could serve as the basis for just this kind of project. I quickly got a call back and the pleasant guy said he could set me up with what I needed (I believe they were R1340s) for surprisingly little money. I should’ve bought the parts because, what, with everybody building their own V-twins these days, the price of donor jugs is bound to go up and up.

    I’m still trying to resolve some issues with my hand-built 43cc V-twin.

  10. Nortley says

    I can see this thing ripping great chunks out of Juneau avenue and slinging them into lake Michigan.

    • starmag says

      “Lucky” certainly was, steering that engine around with a wimpy stock 1980 Suzuki GS850 fork, tire and brakes.

  11. says

    Having seen his road legal Dodge V10 bike at Poole Quays Bike Night several times last year being ridden like it was a little moped, I’m looking forward to seeing this one….

  12. David Ryskamp says

    I can’t imagine kick starting that monster, but I saw him do it! I love the sound too.
    He’s a master craftsman.

  13. says

    “Dr. Enginestein” – nice!

    Those heads are incredible.

    Would be great to see his collection alongside Andrea Georgeades’ collection.

    This also brings to mind the Bad Dog engine with a 6″ bore

  14. B50 Jim says

    Incredible! Love watching all the parts move in relation to each other as it runs — I think vibration might be a problem with this engine. But who cares? It’s the effort that counts, and that it runs and runs well. While everyone is ooh-ing and ah-ing over the heads, which Millyard didn’t make, check out the case castings that he did make, using his own patterns, no less. Elegantly simple and shapely; they’re not the flowing works of art Aniket makes for his Musket, but they exude purpose. I also like that he used old-school SUs with remote float bowls. Easy to swap jets and get the tuning just right, although this engine gulps air in 2.5-liter chunks. It makes other well-known V-twis look downright puny. Can’t wait to see what kind of bike he builds to put it in!

  15. MacKenzie says

    Well, I think that monster twin would be incredible in a WIIIIIIIDE track Morgan-style trike – wide …. to keep both front wheels on the ground when blipping the throttle! My V7 Sport rolls side to side quite enough, thanks very much, at a stoplight while giving it a little goose just to hear the lovely sound.

    Imagine the view from the cockpit of either side of that motor …. incredible! It would be cool to have the push rod side facing forward; H-D gets away with rear-facing exhaust ports and that finning looks pretty efficient (but it was designed with an aircraft application in mind. And the sound ……… !


  16. Fred says

    My motorcycling fabricator hero is at it again! Allen builds interesting “stuff”, and one can predict this will be no different. Radial engine cylinders just look great, and Allen has sure got it right. I do wonder what currently available transmission will be able to handle that much torque, but Burt Baker likely would be able to supply something up to the job. Can’t wait to see the rolling chassis for this, but you can be sure it will work, and be rideable.

  17. Domenique Hawkins says

    Guys, please put this engine on something and post a video of it please. Thanks in advance.

  18. says

    The British version of Pebble Beach is called The Salon Prive. It’s held at Syon House outside London each year. It’s by invitation only and is not open to the public. It’s a very high class affair. Last year Allen was invited and won the ‘WOW Factor’ award for his 100cc Honda V-twin. This year I’d expect him to win in a new catagory the ‘HOLY COW’ award when his Flying Millyard hits the show circuit.

    • Allen Millyard says

      My completed “flying Millyard” was entered in this years Salon Prive and won Best in Class and the “Most Over The Top vehicle” award :)