380 BHP/Liter...40 years ago

Discussion in 'Old's Cool' started by Jinx, Dec 5, 2008.

  1. Jinx

    Jinx Call me Renzo

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    The amazing Suzuki RP 68 50cc Grand Prix Triple

    [​IMG]

    Rotary Valve two-stroke with 3-cylinders in a V configuration (2 horizontal...1 vertical)..each yielding 16.6 cc (that's 1 cubic inch) of raw stump pulling torque :brow

    [​IMG]

    Actually, all 3 couldn't pull the cap off your head....but at 20,000 rpm it made 19 BHP :huh

    And it had a power band narrow and sharp enough to cut diamonds

    So how to keep it on the boil? How about a 14 speed gearbox :deal

    [​IMG]

    Specs?

    Bore = "Not much"

    [​IMG]

    Stroke = "Pretty much fuck-all"

    [​IMG]

    [​IMG]

    Racing record....nada. Never raced in anger as the FIM changed the rules that year to limit 50cc bikes to one cylinder and six gears.

    Pity :cry
    #1
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  2. Bloodweiser

    Bloodweiser honestly

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    that's cute :lol3
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  3. WB-PDX

    WB-PDX Long timer

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    Stellar! Thanks for posting this!

    What is it using for fueling? I don't see any carbs...
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  4. Jinx

    Jinx Call me Renzo

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    Sadly, there are almost no photos of the complete bike available...it is the holy grail of teacup GP bikes. Since the bike itself had no racing history, Suzuki probably crushed it when the rule changes made it a technical dead-end :cry

    But you can see where the inlet manifolds mounted over the rotary valve covers...

    [​IMG]

    ...(the other rotary valve is, of course, on the other side of the engine)

    The previous year's twins used carbs with remote floats, but the triple used Mikuni VM monoblocks. And I am going to crawl out on a limb here and guess that they were...

    ...really fucking small :D

    Here is a picture of the LH side of an RS 67 (125cc V-4) which shows how the carbs were probably arranged

    [​IMG]

    The bike was an amazing piece of engineering: The shot below shows how oil lines fed all the critical parts directly (Main bearings, gears, transmission, etc). A far cry from pre-mix and hope for the best. I count 9 lines coming off a single pump :huh

    [​IMG]

    A pity it never turned a wheel in anger. It was reported that Suzuki had plans to develop it to 25K RPM, though they thought the powerband would be so narrow (less than 500 RPM) that an 18 speed gearbox would be required to achieve those speeds. Cheers.
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  5. WB-PDX

    WB-PDX Long timer

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    I love this thread.
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  6. norton73

    norton73 drinkin'

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    Me too. There was some amazing stuff coming from out back then.
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  7. ROSKO

    ROSKO The Dirty Knacker

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    I've been chasing shadows with the classic 50cc racing itch for a few years now. Finally started building my own chassis this year. Really amazing to see the technology that came out of a world class 50cc series. Imagine moto gp with 50's. Crazy stuff. Lots of homebuilt specials up against the big companies, think jamathi, hemelya, etc. Space frames, monocoque, crazy gearboxes and retarded engine speeds. Shite, the landspeed record for 50cc was just broken this year, kreidler held it since their one visit to bonneville 60's! In europe they are seeing a resurgence of this class in classic road racing and here in the states the USCRA has the only classic/ supervintage/ modern 50cc classes that I know of. WERA also runs a 80gp class which is mostly cr80's dropped into rs/tz125 chassis. Very cool. If anyone is interested to find out more there is an AWESOME thread on the whole era over at the f1 forum: http://forums.autosport.com/showthread.php?threadid=98711
    [​IMG]
    I can't even imagine the sound that came out of this little thing at 20,000+ rpm... pound for pound it puts an f1 to shame I'm sure.
    #7
  8. Jinx

    Jinx Call me Renzo

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    So what drove the Suzuki lads at Hamamatsu to such flights of engineering extremes?

    Well, we would think that Yamaha would have been their natural rival. But for some reason Yamaha never had much interest in 50cc racers.

    Nope...it was mighty Honda. Specifically the RC115 50cc Twin...all 130 lbs of it

    [​IMG]

    And the later, even faster, RC116

    [​IMG]

    Think Honda was playing around? That is not a giant front brake...that is a wheel fairing. The actual brake was a bicycle type arrangement that acted on the aluminum rim. And deep sumps are not something people invented in the last decade

    [​IMG]

    But Honda was always about the engines, and they reached their pinnacle in the 1960's with the RC116

    Bore = 35.5 mm

    Stroke = 24.14 mm

    16.5 BHP @ 21,500 RPM...Redline at 22,500 RPM

    And that is 320 BHP/Liter :gdog

    [​IMG]

    [​IMG]

    Yes...that's a dry clutch

    Yes...those are flat-slide semi-downdraft carbs (And, yes, they are Keihins. Just 40 years older than the FCR model they sell today)

    And yes...it is mostly magnesium (except, obviously, the cylinder head)

    And just because the cylinders were little didn't mean Honda was going to go all cheap-ass and crude. It is still a four valve per cylinder design...they just happen to be very small valves (13mm In / 11.5 mm Ex...3.5 mm stems)

    [​IMG]

    It amazes me today when I see sharp edges on piston crowns...Honda knew better. They were also making the transition to much narrower valve angles...56 degrees by now. Yes, even narrower is better...but not in an air-cooled engine. Close the angle between the valves of an air-cooled engine much less than this and you can't cool it properly.
    #8
  9. Jinx

    Jinx Call me Renzo

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    Very cool...thanks :thumb

    Never know what you will find on the interwebs :evil

    <object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/s4PA8VFpUlc&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/s4PA8VFpUlc&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
    #9
  10. norton73

    norton73 drinkin'

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    :lurk


    Edmucate the unwashed masses
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  11. ADV8

    ADV8 Taumarunui..Darwin..

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    Great thread for sure. :thumb

    Hugh Anderson


    <table class="wikitable" style="font-size: 95%;"><tbody><tr><th>Year</th> <th>Class</th> <th>Classification</th> <th>Machine</th> <th>Victories</th> </tr> <tr> <td>1960</td> <td>350 cc</td> <td>7th</td> <td>AJS</td> <td>0</td> </tr> <tr> <td>1961</td> <td>350 cc</td> <td>-</td> <td>Norton</td> <td>0</td> </tr> <tr> <td>1962</td> <td>50 cc</td> <td>7th</td> <td>Suzuki</td> <td>1</td> </tr> <tr> <td>1962</td> <td>125 cc</td> <td>-</td> <td>Suzuki</td> <td>1</td> </tr> <tr> <td>1962</td> <td>350 cc</td> <td>14th</td> <td>AJS</td> <td>0</td> </tr> <tr> <td>1963</td> <td>50 cc</td> <td>1st</td> <td>Suzuki</td> <td>2</td> </tr> <tr> <td>1963</td> <td>125 cc</td> <td>1st</td> <td>Suzuki</td> <td>6</td> </tr> <tr> <td>1964</td> <td>50 cc</td> <td>1st</td> <td>Suzuki</td> <td>4</td> </tr> <tr> <td>1964</td> <td>125 cc</td> <td>-</td> <td>Suzuki</td> <td>3</td> </tr> <tr> <td>1965</td> <td>50 cc</td> <td>3rd</td> <td>Suzuki</td> <td>1</td> </tr> <tr> <td>1965</td> <td>125 cc</td> <td>1st</td> <td>Suzuki</td> <td>7</td> </tr> <tr> <td>1966</td> <td>50 cc</td> <td>4th</td> <td>Suzuki</td> <td>0</td></tr></tbody></table>

    I wonder if any of the technology Suzuki "borrowed" from MZ went into the 50cc,the 125 certainly went faster overnight and later on, the RGB500 (two MZ 250's)
    #11
  12. Jinx

    Jinx Call me Renzo

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    What could we do today?

    Soooo...anyone up for a 45 BHP 50cc triple? :deal :huh :deal

    A most excellent tiddler site

    Superb site for 1960's GP Honda
    #12
  13. ROSKO

    ROSKO The Dirty Knacker

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    for anyone humbled by the homebuilt specials of the day, Herman Meijer(sp?) who made the ENGINE, TRANS and CHASSIS of the hemelya 50cc GP bike has a website documenting the build, tech and design of the machine. For the weekend builder/ machinist/ welder/ racer this is very inspirational, pardon the long link site is dutch and I list the googledtranslation... check it out:
    http://translate.google.com/translate?client=tmpg&hl=en&u=http%3A%2F%2Fwww.hermanmeijer.nl%2Fhemeyla%2Fvertaal%2520uk.html&langpair=nl|en

    monoshock:
    [​IMG]
    rotary:
    [​IMG]
    no factory, this is homeshop made:
    [​IMG]
    watercooling:
    [​IMG]
    how does a homemade six speed work?
    http://www.50c.nl/animatie-2.html
    and of course the chassis:
    [​IMG]

    anyway, I could go on and on. I have over 400 50cc images saved on my hard drive. Talk about nerding out eh??
    #13
  14. mark1305

    mark1305 Old Enough To Know Better

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    Those 50cc machines fascinated me back in their heyday in the 60s, and still do. The Youtube clip from thre IOM TT is priceless.

    In the mid-2000s Honda was selling a reissue of their CR110 labeled the Dream 50R. (For about $10 Large, IIRC). Strictly a race bike, I saw one in action when I rode in the 2005 True Grit Rally. A young man from Japan had managed to bring one over, get it tagged somehow for the event, and rode it.

    Here are some pics that barely show it after the Rally
    [​IMG]
    The owner/rider from Japan brought an interpreter with him from Japan since he spoke little or no English. That's dedication to an event!


    My old YSR50 next to it :evil Wish I had taken more pics of it. I was in awe of it. It looked just like the '62-67 CR 110 50cc GP bikes. (Except for the required legal stuff like mirrors and lights)
    [​IMG]
    #14
  15. Bloodweiser

    Bloodweiser honestly

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    this is one of the greatest things I've been introduced to in a while :deal

    Rosko - that link didn't work for me. :dunno sounds really interesting though.
    #15
  16. crazydrummerdude

    crazydrummerdude Wacky Bongo Boy

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    Every day, I learn something new on here. :D
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  17. ROSKO

    ROSKO The Dirty Knacker

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    try this: http://www.hemeyla.nl/ it's dutch(?) so look for a tab TECHNIEK then choose motor, chassis etc.




    NOW, for anyone who wants to imagine what the 50cc triple must have sounded like....
    a Van Veen Kreidler (single) at 16,000+ rpm:
    <object height="344" width="425">


    <embed src="http://www.youtube.com/v/8QdSfDELCH0&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="344" width="425"></object>
    now open that in three windows and play all at once!
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  18. DaveTheYank

    DaveTheYank Been here awhile

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  19. datchew

    datchew Don't buy from Brad

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    the geek in me left over from dynamics class is trying to wrap my head around the loads those wristpins are seeing from jerking back and forth that quickly and the stress on those moving parts from such speeds.

    That's insane. Those numbers are outside of the limit of being able to have a "sense of them" and are so high, they're just numbers. Just numbers.

    holy crap. Very cool stuff.
    #19
  20. mark1305

    mark1305 Old Enough To Know Better

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    Datchew, just think for another minute how the engineers that designed much of this stuff in the 60s were probably doing the majority of the calculations on slide rules!!!
    #20