Yes it's subjective, But Which would you consider one of the most reliable engines made? (bygone or present). something bullet-proof, that can go the distance - easy to maintain - with globally sourceable parts (to a degree) . Here's the consensus so far: Bikes Yamaha XS 650 Yamaha XT 225/500/600 Yamaha TT500 Rotax 250/650 BMW K75 BMW Airhead's BMW Twin Shock Air Heads (points) Guzzi Round-fin Guzzi Nikasil Barrel Kawasaki 400/440's (70's-80's) Kawasaki ZX14 Kawasaki KZ1000 Suzuki GS650G/850G (Mid 80's) Suzuki DR650 Honda XR650/250/400 Honda 750/900/1100 Honda CB750/900 (70's-80's) Honda GL1100/1500 Honda XL650V Honda XRV750 Honda 125/150 Step through Moped Indian 74/80" Springfield (flathead) Jawa CZ250 Cars Toyota FJ40 Toyota 22R Ford 302 straight six 60's Slant Six Land Rover 2.25 (petrol) Lister CS diesel Mercedes 617.xxx series (deisel)
Ajax Oilfield engine. www.youtube.com/watch?v=27sL4PXF0dQ 440 Cubic inch single cylinder cross head two stroke. 20 horsepower, at 400 RPM. Weighing only 5,200 lbs. 10,000 hours (That's over 12 months continuous) between oil changes 200,000 hours between re-ring. Typical sevice life - 40+ years Most parts still available. I'm pretty sure I could get 3 more HP out of it with a tuned pipe, but the pipe would be around 36 FEET long
Here's a few: airhead BMW boxer twins, Goldwing GL1100 , Honda 750/900/1100 DOHC fours from the 70's/80's, Honda GL1500 six, DR650 Suzuki, Kawasaki KZ1000 DOHC fours from the 70's, all these are pretty tough. Anything will hold up a long time these days, just change the oil frequently.
Toyota 22R, 60's slant six, benz diesel, oh-oh the guy with the 66 volvo with acouple million miles on it .........What, you didn't specify motorcycle only? oh, okay: it's gotta be some BMW airhead or an old Goldwing.
This whole discussion hinges on your defination of "reliable". Reliable as in "I wouldn't hesitate to ride it across the county"? Or reliable as in "I would not only not hesitate to ride it across the country tomorrow, but I fully expect to do it every year for the next 20 years". I had no qualms about riding my massively modified Mach III from SoCal to Ohio and back. I knew, however, that it wouldn't do that indefinately. My /5 will.
I did say it was subjective However, I suppose I intended the question as in - a long haul bike, across the country and beyond. a work horse suitable for an RTW trip if need be.
Okay then, I vote for twin shock airheads - with points. The only time my /5 stopped running was on a trip was when the aftermarket electronic ignition took a dump. I pulled off the highway and put the stock parts back in, and rode on. They don't make enough horsepower to hurt themselves, they're simple, and easy to work on.
Stock 74 and 80 cubic inch flathead Springfield Indians, just as long as you don't try prolonged speeds of over 65mph .