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Thread: R50S Special Parts?

  1. #1
    Registered User CaptDistraction's Avatar
    Join Date
    Sep 2005

    R50S Special Parts?


    Would someone please tell me, or tell me where I can find, a list of the parts that made the R50S special/ different from an R50 or R50/2?

    I know it uses the air cleaner housing that is the same as an R69S

    I think the speedometer is different, but what is the difference?

    I read somewhere that there is a specific final drive for this bike, but what is the ratio?

    I'm sure it had different carbs, but what are the carb numbers?

    The valve covers are different, so I'm guessing the heads are different as well. Are they the same heads as the R69S? Is there a number stamped in them anywhere to distinguish them from other heads?

    Any difference in the cylinders?

    How about inside the engine? Does it have a different crankshaft? Does it have the vibration damper like the R69S?

    Anything else?

    All help greatly appreciated!!!

    The Captain.

  2. #2
    Cannonball Rider #52 darrylri's Avatar
    Join Date
    Oct 2003
    Surf City, USA (Santa Cruz, CA)
    Some of your answers are here:

    Other than the speedo ratio (W number) and the final drive ratio (7:25), the only other differences between an R50S and an R50/2 have to do with the engine.

    They did not have vibration dampers, as that wasn't added to the R69S until well after the R50S was out of production.

    I think the R50S had 6 bolt heads (like the R69S, and unlike the 4 bolt heads on the R50/2) because of the significantly higher compression ratio (9.5:1 vs. 7.5:1). I'm pretty sure the pistons and camshaft are different, but as it has the same stroke, the crankshaft may be the same.

    The carbs are 1/26/71 and 72, so they are 26mm bore vs. the 24mm bore on the R50/2.
    --Darryl Richman, forum liaison

  3. #3
    Pick up an old parts book (or find one on line... I have a pdf version that I got someplace) and look for parts that have a count in the R50-S column but nothing in any other column to find parts unique to the R50-S. A quick glance at the engine shows different heads, valves, valve covers, air pipes, crankshaft, and pistons. Probably other things that I missed, too.

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