Radial Engine Motorcycle #2

Radial engine motorcycle

The radial engine is a thing of beauty and it looks like several other folks think the same thing. After we posted the radial motorcycle yesterday, we contacted Rotec Engineering, makers of these 7 cylinder radial engines, and according to them, there are at least 4 of these projects in various stages of completion at the present time. Yesterday's bike and this one as well seem to be a bit short of running. I see no provisions for exhaust yet and no front brakes. This bike has no handlebars either so we're still in the building stage. At first glance, you wonder if these guys are serious but these do seem to be real works in progress.

UPDATE: Additional closeup photos on yesterday's post show exhaust pipes behind the engine and at least a foot brake pedal so it may be running as is.

This longitudinal engine arrangement seems more natural for a motorcycle, better clearance for cornering, however, cooling the rear cylinders would definitely be a problem. Yesterday's transverse arrangement is great for cooling and correct for the engine's design but it presents clearance problems, not only straight up for the bottom cylinder but when leaned in either direction, as well.

I can't believe these bikes will be much more than showpieces when done, who could actually ride them? Still, I think radial engines are among the best looking engines ever designed and these Rotecs are small enough to put in all sorts of different things, airplanes look great with a big radial out front but there are always cars, trucks, boats, you name it. But you have to give these guys credit, a radial engined motorcycle, superb!

Again, if anyone has specifics on these motorcycles, please let us know.

Update: Radial Engine Motorcycle by JRL Cycles

Also, thanks again to Jeff for the photo.

Link: Rotec Engineering

The Kneeslider: Radial Engine Powered Motorcycle
The Kneeslider: Model Radial Engines


  1. hoyt says

    an old pickup with a larger displaced radial engine on display under the hood (with open sides) would be cool

  2. aaron says

    I’m a little disappointed, I wanted to do this first! (well, after the killinger and megola, the 30’s were a lond way away…

    this guy (#2) has gotta be serious – those goldammer forks alone cost, what, ten grand? (and I remember the price from when the american $ was at $1.60 cdn – it’s around $1.10 now – so the fork may have increased similarly in price. those things start with about a billion pounds of aluminium before they start machining!)

  3. hoyt says

    likewise on the other bike…the WCC frame alone is over $4k. Well, serious is a relative term. Serious about posing.

  4. JT says

    Here’s a perfect example of : “Just because you *can* do something…Doesn’t mean you should” Silliness abounds in Austrailia!

    JT and Dave

  5. kneeslider says

    Sure it’s a bit silly, but that’s my kind of silly. Just think of how many motorcycles start with nothing but a dream, a welder and a case of beer … :-)

  6. says

    I found his website at JRLcycles.com. This guy is an airplane mechanic in Sturgis South Dakota. He has cool T-Shirts too. Can’t wait to see the bike in sturgis this year.

  7. Spanky says

    This bike is awesome…anyone know more info on if its available for sale or if the parts are being sold thru JRL cycles…i called rotec and they say that jrl is the only distributer for the engine if its for motorcyle use….not much usefull info on thier website but i did read on another blog that it is much farther along and will be at oshkosh airshow and sturgis.

  8. Dan Hudson says

    Awesome bike! I drew detailed drawings of a roadrace one back in about 1978 which I still have filed away. I would love to put a smaller engine version of this into production. I love it.

  9. Scott says

    That is the coolest “alternative” engine I have ever seen. I hit up a buddy at the airport last week for a helicopter turbine. Guess I was on the wrong track.

  10. Karl says

    Thank goodness he didn’t have a rotary engine laying around! The “throttle” on one of those is a kill switch: either it is running or not! That would have been fun in traffic!

  11. TriumphGuy says

    I looked at the new pictures on the website and I am a bit disappointed. At least the old Feuling W3 with its tried and true swingarm was meant to be ridden. Lift the seat a little, put a U shaped swing arm on that thing, perhaps set a small centrifugal fan concealed in or behind the pulley and make this thing a little more practical.

  12. blaine says

    so quick question i work in an helicopter engine shop and a bunch of us were wondering how do u keep the oil from building up in the 6 o clock cylinder?

    and advice would be cool to know..


    Blaine Canty

    by the way that is one bad ass bike…

  13. Jesse says

    Jesse James built one of these, I think it’s the first pic you posted. Cycle World Magazine ran it this month.

  14. Texas Skull says

    Doesn’t it have a monstrous amount of torque? Especially on the bike mounted the other way.

  15. John Dozier says

    Name any engine, and someone will crack open a beer and put it to a use other than what was originally intended. Sometimes it’s a joke, and every now and then it’s a work of art. Cooling will be a problem but not an insurmountable one. A little creative work on the intercylinder baffles will direct air around the cylinders, although you might not want to idle very long.
    As for oil pooling in the lower cylinders–on aircraft we pull the prop through slowly for as many compression strokes as you have cylinders. For this beauty you could pull the lower plugs and drain the cylinders. To really make a mess, pull one plug from each cylinder and spin it with the starter…
    Just remember, if a radial isn’ leaking oil, it’s empty.

  16. says

    Have a picture of radial #2 as a finished bike. It is fantastic. Handlebars and tank blend smoothly over the top of the sideways mounted radial, dropping back to a nice fat rear tire. It’s finished in a metallic blue. Am thinking since it is a radial, the torque of the engine on the side-ways mounted engine would be less effect on the bike handling.
    As for oil pooling in the six o’clock cylinder, no more of a problem here than it is in an airplane. VR. Mags

  17. Phil Marks says

    Response to Scott, May 20th:
    Jay Leno thinks you guys were on the RIGHT track and wrote a cheque to back it up! He runs a bike with a helicopter turbine power plant. I’m not sure if it’s a P&W, Allison or what, but according to his column in Octane magazine, it is fully functional and road-legal. Hot exhaust tends to melt plastic bumpers on cars behind him at the lights. YAHOO!

  18. Tim says

    The question about the 6 O clock cyl and the oil build up.

    The Cyls. on a radial engine have a long skirt and the scavenge pump picks up the oil leftovers while running.

    If the engine is left Idle for a long time, the oil will drain past the pistons in the lower cyls, and can cause a hydraulic lock on start up.
    Aircraft engines of this type must be turned over by hand before starting.

  19. Jim says

    These Radial powered bikes are great. My own fantasy is to build a monster airboat with an R-2800, R-3350, or incredibly a R-4360 on it and blast down the Sacramento River from Sacramento to San Francisco. The sound would probably give me a coronary!

  20. Mark McCausland says

    I believe that those engines are made to spin in an aiplane but on these bikes they stay where they are and the shaft spins. Is this correct? Also, would they be using only a few of the cylinders or all of them?

  21. 1966norton boy says

    man this is an engeneering marval…
    u can fix head both vertically & horizontally…
    its cool…
    iam not lucky like you guys …
    but some day i will catch u…….