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V-Twins in Featherbeds

Discussion in 'General Classic Motorcycle Discussion' started by Bernhard, Mar 25, 2014.

  1. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
  2. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    If you've ever raced a bike with a featherbed frame, you should know how important the weight distribution is. With a Triton, even though you can get the motor well forward, a manx will always handle better because of where the motor sits. Back in the 50s, there was one Victorian rider who raced a Norvin, and was able to win races against the manxes - why would anyone bother ? A big blast on a vastly over-capacity bike does not prove much. It was something which set a precedent in Australian road racing, and a reason our current historic classes are so stupid. There was a race bike 880JAP/featherbed racing here about 12 years ago, it was not something that I would ever try to ride in a race, a triton is bad enough. It is easy to find yourself in a 70 MPH corner with the bike feeling vague in the front end and twitchy - it really destroys confidence and stuffs your riding technique.
    Those sidevalve motors in featherbed frames are the way to go - probably would not bite you.
    I like this better:
    http://www.youtube.com/watch?v=UbUrIwA9jVE
     
  3. lcrken

    lcrken VIP MEMBER

    Joined:
    Mar 15, 2009
    A couple more examples.

    The Fitzpatrick BSA twin.

    [​IMG]

    Another HD engine in a featherbed.

    [​IMG]

    And the Sporton. I think this was a replica featherbed frame built for the Sporton, not an original, but I could be remembering wrong again.

    [​IMG]

    Ken
     
  4. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
  5. xbacksideslider

    xbacksideslider VIP MEMBER

    Joined:
    Aug 19, 2010
    Thanks Bernhard.

    I enjoyed that.
     
  6. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
    [​IMG]

    anyone identify the injun type ? not a Howard J.A.P. rotovator bottom end ? :mrgreen: :?

    Was the notorious J.A.P. Hagon Vee Twin F'bed Drag Race Machine in the little green ' Raceing Motorcycles ' book from the 60s , too .
    [​IMG]
    Er . . . " SPRINT " bike ! . :oops: :lol:

    [​IMG]
     
  7. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
  8. Rohan

    Rohan

    Joined:
    Aug 26, 2010
  9. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
  10. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    You wanna play, ya gotta pay....
     
  11. wilkey113

    wilkey113

    Joined:
    May 6, 2010
    Couple of those bikes are well done and nice looking, while the majority of them are pure rubbish
     
  12. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
    WHY ! I remember when you could buy a Brough Superior for 15 pounds ! ( Not Really , but that WAS the case , at one time )
     
  13. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
    THATS not a Vee Twin ;

    [​IMG]

    THIS IS a VEE TWIN : :D

    120 x 120 . 20 Hp . :) ( 90 mph )
     
  14. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
    J.A.P. Vee Four ! . 1910 35 Hp.

    [​IMG]
     
  15. ashman

    ashman

    Joined:
    Jul 11, 2010
    Great pics, I just love Featherbed frames, widelines or slimline don't matter to me, it don't matter what goes into them (hopefully they will be bristish motors) if they are set up right and of course I do mean set up right, they will be one of the best handling bikes on the road, but I think cutting the bottom of the frame away to fit motors is sacerlege (is that how you spell it) to a great frame.

    Ashley
     
  16. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I watched Bob Jolley race the 880 JAP/featherbed at Winton some years ago. It was OK, however seemed to pull harder than it needed to, with not enough top end. The Norvins were better at the time, however none of them would be a pleasant ride. It makes a big difference how far forward you can get the weight with a featherbed framed bike. The bikes in the photos look great, and in theory should be good to ride. However the practice sometimes doesn't reflect the theory. It is never as simple as just fitting a motor into a frame.
    I can remember a time when I found it impossible to get a respectable lap time with my short stroke Triton. I moved the motor forward until the front engine mounts touched, and the bike stopped feeling vague in corners. That restored a bit of confidence. I look at some of those photos and recognize the potential for getting a hard time. I crashed a lot when I was a kid.
     
  17. ashman

    ashman

    Joined:
    Jul 11, 2010
    Over the years I brought a brand new 91 1200 Sportster , but only had it for 3 years, I liked the power of the 1200 but a HD was just not my bike, but the last year or so I have been thinking about what it would be like to put a 1200 Evo motor in a Featherbed, be a lot lighter than a cast iron motor, I have a spare Slimline Featherbed all I need is to find a cheap 1200 Evo motor :roll:

    Ashley
     
  18. Matt Spencer

    Matt Spencer

    Joined:
    Jul 25, 2010
    [​IMG]

    Reading a antique book on J.a.p. , well - 1952 - says the twin good for 95 Hp . :D :twisted:
     
  19. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Really depends on how it is set up. If it is nice and torquey with high gearing , and a close box it might be quite good. If it is savage with wide box, and not so high gearing, it could give you a really hard time. The problem comes when you are cranked over going really quickly in a bend and have to change gear or it drops off the power band because you have backed off too much, and you have to slip the clutch to keep it going. A bike like that is capable of tying itself up into a knot, and launching you. A 95 BHP featherbed V twin is not a kiddies' toy. I would ride it, however I'd be very careful if I started to get inspired.
     
  20. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    95 hp sounds rather optimistic, to say the least.
    JAP claimed 80 bhp - thats where the 80 in 8/80 comes from.

    Do race high-compression JAP twins have a 'powerband' ?
    The expression 'pulls like a train' comes to mind.
    There are published dyno charts for these as the earlier versions,
    and the torque curve is pretty strong.
     

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