The Flying Millyard V-Twin - Building a proper frame for an enormous engine is no easy task

Allen Millyard's Flying Millyard Boardtrack Racer

Allen Millyard's Flying Millyard Boardtrack Racer

An email arrived the other day from one of our readers who had just returned home from the Cassington Classic Brit Bike Show. He'd just taken a few photos of Allen Millyard's giant boardtracker, the Flying Millyard, built to house the engine he had created using two cylinders from a Pratt and Whitney 1340 radial. The result is a 5000cc V-Twin and it's a beauty to behold.

Allen doesn't seem to take a lot of photos of his own bikes, but he does take videos, so these photos, along with the videos I've included below, gives you an idea of of what he's done.

To begin, the bike, at idle, has the pleasant sound of an old radial biplane idling on the taxiway, if you've ever heard an old Waco or Stearman, you know what I mean, and on the road it seems to cruise without effort, as a 5 liter V-Twin certainly should. The Flying Millyard, though, does show one shortcoming of building engines this big, and that is, trying to get the proportions of the bike right when it's going to be ridden by a normal human being. The engine can't be squeezed into a normal frame of any sort, so you end up getting an outsized lump in the center with very long handlebars for the rider out back.

Allen Millyard's Flying Millyard Boardtrack Racer

Allen Millyard's Flying Millyard Boardtrack Racer

As I look at this bike, I wonder if turning the engine sideways and letting the cylinders flow through the air as intended, might be a better option, not only would it would look like a huge Moto Guzzi, but the cooling fins would work better, too. There would be some space taken up by the transmission, however that was handled, but you might be able to shorten the bike a bit in the process. I don't know, but a few sketches on the back of a napkin might be time well spent. Of course, Allen may have thought of that and ruled it out for other reasons and anyone who can build engines like he does is free to do with them as he pleases, but the thought does cross my mind when I look at this. Hmm, ...

Thanks for the photos, Nigel! They're much appreciated.


  1. Clive Makinson-Sanders says

    Its hard for me to wrap my head around left side driving and it scares me every time i see it from the drivers perspective. Aside from the size of the bike, which i agree has that pregnant beach cruiser look, ive never been a fan of angular tanks. BUT ive also never built a 5000 cc engine with my own two hands.

    • Hooligan says

      And how do you think people who drive on the left manage with swopping to the other side of the road? Like if I like millions of others, get off the ferry from England and drive on the other side of the road in Europe even with the steering wheel on the “wrong” side. We manage. Human beings are adaptable and their brains can cope. Bikes are even easier.

      • Clive Makinson-Sanders says

        I know, its just when i see him going around blind left curves its scary.

  2. Leston says

    Turning this engine sideways and ditching the flying merkel theme would create such a better bike visually. But like everyone has said, i have not and cannot build a 5000cc engine. This engine is gorgeous and the head fins are sexy.

  3. Kayjay says

    As a total non-engineer, maybe torque effect on such a large engine could be problematic.

    • Giolli Joker says

      I’m a mechanical engineer but I’m nowhere near the understanding of engines that Mr Millyard masters… however, I’d agree that torque could be an issue with a longitudinal crank shaft.
      On the other hand, though, the very same Millyard made a rideable naked bike around a Viper V10, so nothing would be impossible (for him).

  4. blackbird says

    Another great engine from the master. On the subject of turning v-twins sideways I’ve remarked to several Harley riders about why I’ve never seen one of those turned the other way? Seems to be a natural thing to do with that narrower vee angle and would keep the (now) rear cylinder from baking.

    • says

      I thought the same for years, but those motors are slightly taller than a Guzzi (except for the latest CA) so knee clearance for a cafe or standard bike could be problematic. The better solution is to put an oil cooler on a HD powered bike.

      I still wonder what an X-wedge motor would look like turned sideways on a cafe bike (mated to a Motus tranny). That motor is more symmetrical so it lends itself to facing forward w/the jugs in the wind

  5. Mike Michaelsen says

    A superb engineering job to say the least and I tip my hat to Mr. Millyard.
    I personally would rather see a smoothwer tank design but Allen built it and Allen can have whatever design that appeals to him!

  6. GenWaylaid says

    I love that name. “Flying Millyard” evokes the power required to launch an entire lumberyard through the air.

    Turning this engine sideways could improve the packaging, but I don’t know if it would be comfortable. One of my bikes is a Honda CX500, a “flying V” design. Honda addressed the torque reaction by spinning the clutch and transmission opposite the crankshaft, cancelling a large portion of the angular momentum. Side-to-side vibration, however, remains a problem at middle RPM. Even with a narrower V angle, the Millyard’s reciprocating parts are so massive that the vibration could be unbearable if the engine was sideways.

    This engine would be awesomely absurd on the front of a Morgan-style three wheeler, though.

  7. says

    I’d say he’s made a fantastic job of wedging that donk into a frame. Nobody has mentioned that by running it fore and aft he has kept it nice and slim. Also, if the smaller Guzzi engine give that torque reaction then imagine what 5L gets you…

    It certainly seems to go down the road quite nicely and was getting through the corners fairly nicely for such a monster.

    Love the madness and the fantastic engineering!

  8. Sportster Mike says

    Love this bike – saw it on Poole Quay’s Bike Night a few weeks ago – ridden in 80 miles!!!

    From the back it looks just like a little Bantam until you see it sideways and see the engine!!

    Allan took a spanner/kickstart lever from his back pocket and spent the evening kicking it over….

    I had the same problem taking pics as Nigel – lots of people around it and I too was chopping peoples heads off

  9. Sportster Mike says

    Just seen the video – typical B road with crap all over it – just like Dorset…

  10. B50 Jim says

    Total overkill — and why not? He had the chutzpah to build that monster engine, so he can put it in any frame he bloody well pleases. It certainly evokes the spirit of the board-track racers, and it isn’t intended to be practical, just a crazy machine that will turn heads wherever it goes. I can’t imagine how that much torque feels!

  11. SKoo says

    Notice the size of the primary gear sprockets? The clutch shaft spins faster than the crankshaft.

    Seems to have just a clutch, no gearbox. In the second movie, at a speed of 70mph the engine still seems te be idling.

    Wonder how the beast sounds at full acceleration.

  12. canbalen says

    This gives a true meaning to the word Motorcycle jjjjj according to the numbers from the original engine with his 9 cylinders and pushing between 420 and 600 hp this beast must make from 100 up to 240 hp , so it could have a topspeed well over 130 mph , take it to the strip please go on allen

  13. mean monkey says

    Allen Millyard is a great builder/doer! I really enjoyed his SS-100 bike featured here.

  14. Allen Millyard says

    To answer a few questions, I wanted to create a 1930’s style board racer with a big engine, front to back it had to be to keep it narrow. It has 4 forward gears and reverse. The bike is geared for 120mph at 1950 rpm. Power is probably around 80 to 100hp due to lower compression and no supercharger. I’ve ridden it over 600 miles on the road so far with 150 miles in an evening on several occasions. The ignition and mixture is manually controlled via a pair of tank mounted brass levers.