Every time I hear a Harley idling at a stop sign I get the idea that the loud low-RPM thump-thump is the most appealing attribute of the Harley to many of its afficianados.
I have an idea to take the slow thump to the extreme. It would take lots of dedication by a skilled engine builder, but if it worked it would create a sound much more outrageous than that of a Harley. All that is needed is a cylinder and a head and a piston from a radial engine from a WWII bomber. Most of these engines had 9 or 14 or 18 cylinders, and up to 200 cubic inches per cylinder. Bores were as large as 6", and strokes were as long as 7".
The engine builder would have to design and fabricate a crankcase and a crankshaft and a connecting rod and a camshaft and a big heavy flywheel.
To maximize the effectiveness of the flywheel and keep it reasonably small, it might be gear-driven and spin faster than the crankshaft. This might also make it easier to mate the engine to an existing motorcycle transmission.
The engine would necessarily be very long, but if the bike was a chopper style, there would be plenty of room to mount the single cylinder horizontally.
A lot of work for someone, but it would sure sound cool if someone could pull it off!-- RunVentura, Oct 04 2006 "pop-pop" http://auto.howstuf...com/question325.htm [Shz, Oct 05 2006] Radial Engine Motorcycle http://thekneeslide...powered-motorcycle/build by Jesse James, I believe [discontinuuity, Apr 16 2007] 410 cubic inch V-Twin http://thekneeslide...torcycle-completed/The same thing, but more! [discontinuuity, Jan 04 2013] It's not just the slow and low thumping that gives a Harley that beloved sound, though. It's that the pistons don't fire at equal intervals. It goes thump-thump...thump-thump instead of thump.thump.thump.thump.
Lower and louder isn't enough to shame a Harley, I'm afraid. This is missing the legendary thumpin' uniqueness.-- Shz, Oct 04 2006 Sounds good. It would have the same salient features as a Harley: Efficient noise production, with the side effect that it can be used for transportation.-- undata, Oct 04 2006 Large single cylinder engines have been baked by several manufacturers.
The eastern-bloc manufaturer Ural even made a diesel motorcycle too.
You might like the sound of Harleys, but they are as unreliable as hell. I'll stick with my bike thanks ;-)-- webfishrune, Oct 04 2006 Oh, now you've done it [webfishrune]. Take cover, and prepare for the Harley enthusiasts to shell your position.
From what I've heard, the later generation engines are actually pretty good, it's the early stuff that was "four hours of riding, one hour of maintenance".-- normzone, Oct 04 2006 Harley Davidsons are nice for people who like to spend money on noisy and mostly broken-down old stuff, with the added bonus of being able to stick Village People-type concho-encrusted accessories (not that I have a problem with such accessories in general - just on motorcycles) on them, but surely a proper motorcycle is beautiful, usually made in Italy, screams like a banshee, goes stomach-clenchingly fast, weighs less than a small moon (unlike a Hardly Rideable), costs less to run than the space shuttle and will start and continue to go in the rain.;)
I'm already feeling the hate.-- Murdoch, Oct 04 2006 Ah yes...I remember a scene during one Daytona Beach bike week.
A harley guy was outside, trying to start his bike. Kick-start, thumpata- thumpata- thumpata- cough- wheeze- silence. Tweak the carb. Try again.A clean-cut guy walks out of the bar, climbs on his Honda Goldwing. Harley guy looks up, asks Honda guy why he'd choose to ride such a "pussy bike". Honda guy turns the key. ReeReeReekakathupthupthupthup "That's why." replies Honda guy, as he rides away.-- Freefall, Oct 04 2006 Sounds familiar. Y'gotta ask why one would buy a second-hand motorcycle for £4,500, then spend a fortune on getting it stage-1ed, as I'm told it's called (basically, bore out an 883cc engine to 1200cc, from what I can gather - why not just buy a bigger bike?), then have to spend LITERALLY thousands of pounds over the next six years keeping the brokedown sonofabitch on the road for more than 5 minutes at a time, as my good mate has done.
Mind you, he had a Norton Commando before that, which was only good for making a great noise on the rare occasions when it would start, looking good, and pissing oil around the place and acting as a moneypit at all other times.-- Murdoch, Oct 05 2006 I certainly would never buy a Harley, modern or otherwise, mostly because they're too expensive and I don't quite fit into the demographic they target (retired dentists and ex-hippies). The only reason modern Harleys run better is because they have ballance shafts to tampen the inherently vibration-prone design.
As for the idea, it sounds like you could bake it, but I doubt it would be practical, safe, or reliable at all. As you said yourself: "A lot of work for someone, but it would sure sound cool if someone could pull it off!"-- discontinuuity, Apr 16 2007 random, halfbakery