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You wouldn't believe this engine!
- Thread starter PAULBACH
- Start date
Polarbear
Polarbear
I know what it is!
Pilot here and seen these in another format....Airplanes! BMW built these engines for a lot of airplanes over the early years. These radial engines are very common WW2 era engine and beyond. Of course BMW got its start building Airpalne engines in the late teens, a tad bit before cycles came along. WW1 dried up and the need for such did, too. Therefore the 1923(I Think) BMW cycle was born from the earlier aircraft engines. Its a tad bit funny looking in this bike picture. Cool work, though. HP and torque here is HUGE! Randy13233
Pilot here and seen these in another format....Airplanes! BMW built these engines for a lot of airplanes over the early years. These radial engines are very common WW2 era engine and beyond. Of course BMW got its start building Airpalne engines in the late teens, a tad bit before cycles came along. WW1 dried up and the need for such did, too. Therefore the 1923(I Think) BMW cycle was born from the earlier aircraft engines. Its a tad bit funny looking in this bike picture. Cool work, though. HP and torque here is HUGE! Randy13233
S
screwtop
Guest
Those radials are really cool. At the Smithsonian Air Museam at Dulles Airport, they have a mechanical virtual "cut-away" of one of those radials and show the crank/flywheel rotating and staggered firing order of the cylinders and other moving parts. Wonder what it was like setting the timing on those things?
BTW - I know BMW began as an aircraft powerplant manufacturing company, hence the roundel that represents a spinning propeller. Isn't it true that after WWI there was a some kind of a treaty signed that prohibited them from building airplane motors, so they resorted to building motorcycles? Can any history buffs confirm?
BTW - I know BMW began as an aircraft powerplant manufacturing company, hence the roundel that represents a spinning propeller. Isn't it true that after WWI there was a some kind of a treaty signed that prohibited them from building airplane motors, so they resorted to building motorcycles? Can any history buffs confirm?
B
BOKRIJDER
Guest
PUDGYPAINTGUY said:
You're right about the original radials this is a later version. Engine is stationary, the crank turns as is normal practice. As stated, HP is huge, torque is AWESOME.
I'm sure that it is intended as a drag exhibition bike. This engine is dry sumped and would normally use a 12-15 gal oil tank with an air to oil heat exchanger. Fuel consumption is just as awesome as the torque output. Bike tank would only last about 10 min. These things are worth firing up just to hear the exhaust note, a very smooth low rolling rumble. I've spent many hours wrenching on radials. Ultra reliable in the air, but require hours of routine maintenance.
Motard
B
BOKRIJDER
Guest
Interesting, on the second bike it appears that they are pulling power off an accessory drive pad rather than off the crankshaft itself. The flywheel effect would be horrendous. Probably a feat to keep it between the barricades. Nor is the engine design intended for acceleration but rather for hours at a sustained RPM.
Anything for a laugh.
Motard
Anything for a laugh.
Motard
H
HODAG
Guest
screwtop said:
yes, Treaty of Versailles
as as I know it
WWII chapter I
manicmechanic
ABC,AMA(LIFE),MOA,RA,IBMW
Stationary cylinders, rotating crank=radial engine
Stationary crank, rotating cylinders=rotary engine
Although both types have cylinders in a radial arrangement.
Stationary crank, rotating cylinders=rotary engine
Although both types have cylinders in a radial arrangement.
sgborgstrom
Don't forget your towel
I thought a "rotary" engine looked like this:
Is there more than one type in the classification?
Whatever happened to the old Norton rotary bikes? I remember reading about a police model in England and some controversy about how to rate it for engine size which eventually led it to being dropped from racing.
Steve
Is there more than one type in the classification?
Whatever happened to the old Norton rotary bikes? I remember reading about a police model in England and some controversy about how to rate it for engine size which eventually led it to being dropped from racing.
Steve
Last edited:
Motard said:
Thanks for the reply and explanation..another tidbit for the databank...very interesting stuff. I would have sworn that it was a photoshop bike, thanks to you and MCMXCIVRS for the explanations and history...outstanding feat of engineering then is what we are looking at to get that much motor into a frame.
B
BOKRIJDER
Guest
You might be right.
Motard
Motard
The_Veg
D'OH!
The engine in both bikes is an Australian-made Rotec, who produce radial engines for aircraft builders who like the vintage touch. The 7-cylinder Rotec is 31" in diameter and produces 115 bhp, which isn't all that horrendous really. BTW it's a $13K engine. I'm pretty sure the second bike is a Jesse James creation. As for the first one's lack of handlebars, it looks to my eye like it's not finished yet.
