1909 Curtiss - some interesting specs

Discussion in 'Antique Motorized Bicycles' started by DougC, Dec 25, 2010.

  1. DougC

    DougC Guest

    This page has a story on a barn-find 1909 Curtiss:


    link text--- http://thevintagent.blogspot.com/2009/05/barn-find-1909-curtiss.html

    Early on in the text he notes-

    Beneath the second photo, a couple of figures are given-

    Further on it is said-


    So from this we can gather a few things:

    For a v-twin motorcycle of the 1905-1910 era...
    ...weight would be ~160 lbs
    ...top speed would be around 65 mph

    Most surprising to me is these two figures-
    ...v-twin engine would be ~1000cc's
    ...that engine would only make about 5 hp (!)

    By comparison, the 2010 Yamaha YZF-R1 has a 998cc 4-cyl engine that makes about 146 HP.
    If you wanted to compare another twin, then the 2011 Harley-Davidson Superlow with an 883cc motor makes "only" about 55 HP. Ten times as much.

    A modern 5.5 HP lawn tractor engine is a pretty low-performance motor, yet displaces only around 150cc's.


    We see a lot of people who wish they could find an engine that would look more authentic than the China bike engines--but the biggest problem you would seem to have would be to keep a modern engine from making too much power....

  2. Hoodoo

    Hoodoo Member

    Old motorcycle engines

    Comparing the old long stroke engines used on the motorcycles of the BTR period (and before) with anything approaching modern engines is american apples vs mandarin oranges. Both are fruit, both are good, but they are different.

    HP ratings alone can be very, very deceptive. A three-four hp (so called) engine from the old days had a lot more torque than the chinese motorized bike engines of today. You had your power for a much broader range. While normal cruising was 15-25 miles per hour in the early days it was a much more comfortable cruise on a somewhat heavier bike than what the modern motorized bikes do and even the old pedal bikes very quickly became solely for getting the engine started, not getting you up to speed where a chinese engine comfort zone is. The chinese engines are pedal assist, the older engines after they started getting up to about 3-4 hp really didn't need it and they did not work as hard once you were up to speed...they could get you up the hills with that torque....and the old bikes were more rugged, as they had to drive on challenging roads.

    The same thing for the early V twins... they called them 10-15Hp and the like, but they were much more powerful due to their high torque. It's never just HP, it's HP and torque and RPM's in a particular dynamic. A lot has to do with the purpose of the machine for the engine.
    Last edited: Jan 22, 2011
  3. MarkV

    MarkV New Member


    Also, it should be noted that manufacturers historically equated their nominal horsepower with a particular displacement of engine. I have run across this in books on old bikes. I think this started out because early on a certain size engine of virtually any make was accepted as making a certain horsepower. As engine technology improved, they got more actual power out of the same displacement but continued to use the old rule-of-thumb HP per cubic inch ratio to describe the newer bikes. Depending on whether the bike is earlier or later in the period when this system of nomenclature was used, the bike would actually have anywhere from the nominal HP up to several times what the nominal rated power would indicate.

  4. Hoodoo

    Hoodoo Member

    Harley 1912 4.3 HP 50 MPH

    I don't know the weight of this motorcycle yet but it doesn't look light yet it's 4.3 hp single cyclinder could get it up to speeds of 50 mph.

    If a 8.5 HP modern engine gets around 50 MPH top speed on a motorized bike, i would think this old 4.3 HP engine really putting out about 10-12 equivalent HP pushing a heavier frame and engine all at an early rating of 4.3HP.

    While the performance might appear sedate, you are talking real motorcycle riding and not souped up bicycle riding.
  5. rustycase

    rustycase Banned

    Thanks, Doug....

    I just lost two hours of my life at that vintagent website...:)
    Gosh, what neat bikes they have there!