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And you think your 250 is small?

Discussion in 'General Motorcycling Discussion' started by hornet, Aug 11, 2005.

  1. Here's a 50cc (count them, 50cc, model aeroplane engines can be bigger than that) Kreidler Grand Prix bike. The manufacturers used to loiter round schools looking for lightweight riders, and once contracted, they were not allowed to eat for the whole season, and had to keep their fingernails REAL short!
    http://www.vintagebike.co.uk/Bike D...2 H - M/pages/Kreidler-50cc-VanVeenRacer2.htm
    (Back then there were 5 classes in GP racing; 50cc, 125cc, 250cc, 350cc and 500cc.) This bike is probably from the early 70's.
    And while you're there, hop over and have a listen to the 1965 Yamaha 125 SOUND file!!

  2. Its what jockeys ride for fun..
  3. The 50's were amazing.

    Before the FIM limited them to a single cylinder, some of the Japanese manufacturers were running multi-cylinder 50's.

    During 1964 Honda replaced their single cylinder 50 with a TWIN. Now facts and figures CAN be dull, but these are nothing short of amazing.

    The Bore and Stroke of this little beast was 33 x 29.2 mm and its peak revs were 19700 RPM Riders regularly revved them to over 20000 RPM. The bike had a 10 speed gearbox and developed 13 bhp and was capable of over 160kp/h

    And, yes, this was a FOUR STROKE motor, with 4 valves per cylinder!!!! So imagine how tiny the valves must have been.

    AND that was 41 years ago!
  4. Pretty good for the time but things have improved since then, you only need to look at the technology in model aircraft engines. A 50cc twin might have been impressive 40 years ago but check out the 50cc flat four, or 5 cylinder radial.
  5. Yeh, but the flat four only revs to 8000RPM and develops only 4 horsepower.
    AND, it only has to pull a light aeroplane though the air, not carry a rider and bodywork around the Isle of Man
    Still nowhere near the technological achievement of the Honda 50. They're not even in the ball park.
    I fail to see how you can call these engines an "improvement"
  6. Well all the moving parts are only half the size and they're mass-produced. They may not rev as high and therefore not produce as much power but I've no doubt they're probably a lot more reliable.
  7. Given the increase in metallurgical knowledge, making the parts smaller isn't that much of an advance, and we're not talking about reliability, we're merely discussing the tecnological ACHIEVEMENT of getting that sort of a motor built and running reliably so that it won races over 40 years ago.

    Again, I stand by my contention. The Honda achievement is still vastly superior.
  8. Apples with oranges comparisons are never pretty; looking at the specs the plane engine is amazing; how small must the valves be, for example? But it's built for a plane, to run at constant revs and constant load, in a relatively friction-low environment. You could never use it in a bike, as noted, but equally, you could never use the Kreidler engine in a plane. Sorry about the bad pun, but, different strokes for different strokes.
    Getting away from the engine for a minute though, how about that MASSIVE front tyre???
  9. Here's some stuff on Kriedler's 200kph 50cc record breaking machine...

    From http://membres.lycos.fr/rebel6/kreidler2.html

    I’ve translated from the French. If any French readers spot mistakes – please correct. Especially the (?) bits since my technical French is non-existent and Altavista's Babel-fish translator is even worse.

  10. So you don't consider this increase in metallurgical knowledge to be a technological advancement in itself? The problem is there's no real current demand for high-powered 50cc engines but I'm sure if someone was willing to spend the money it would be possible to design and produce something a lot more powerful than Hondas 50cc twin. Also check out the 60cc V-8 here: http://www.conleyprecision.com/prod01.htm
    Okay the power output may not be much but that's an impressive number of small moving parts.
  11. Technical achievement ought to be applauded for its own sake, irrespective of application. Metallurgy today is light years ahead of 40 years ago, but that the builders of the 60s were able to do what they did with what they had is in itself remarkable.

    Remember the story about the German company that manufactured drill bits, just before the war? A British company made a drill bit which could drill into the EDGE of an eggshell! Proudly they sent it to the Germans, to show off. The German company sent it back with a note to say, "look carefully at the bit".

    They could see nothing remarkable with it until they examined it under a microscope. The Germans had drilled a hole THROUGH the British bit!!

    But really, guys, apples an oranges, put the soapboxes awway!
  12. lol damn showoffs!
  13. I have heard a variation of that story where an American company sent a Japanese company a peice of metal drilled with their finest drill bit with the challenge 'can you do better?'

    The Japanese company sent back the peice of metal. The American company engineers were stumped, there was only the original hole that the Americans had drilled. They asked the Japanese company for an explanation and were told 'look closer'

    The original hole that the Americans had drilled now had a thread.
  14. Go and have a ride on a Honda Dream 50

    A mate of mine wanted to import them a fiew years ago... top little bikes!! and oddly powerfull...