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Nicht beantwortet Vespa gearing...


Letzter Beitrag Fr, Sep 12 2014 18:02 von heggie. 3 Antworten.
  • Do, Sep 11 2014 13:58

    Vespa gearing...


    Hi,

     

    I have a PX 125 engine with a DR 177 kit on it.  I know the gearbox is standard PX 21/67 primary but it has a 35 tooth 4th gear and basically is struggling to keep its speed up on any inlcine.

    If I want to reduce or shorten top gear to make it rev more, and without taking the engine apart, can I do this by changing the clutch primary gear?  If so do I want to go from 21 up to 22 teeth, OR from 21 DOWN to 20 teeth ?

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  • Do, Sep 11 2014 17:31 Antwort zu

    Re: Vespa gearing...


    to shorten the gearing you want to go down to a 20 tooth.

    what exhaust are you using? it seems like a DR177 should be able to pull and hold 21/67 even with a 35 tooth 4th gear. my stock Stella 150 2T (LML Star 2T) had 21/67  and when i put on a SIP road exhaust i also up geared with a 22 tooth and i have no problems keeping speed.

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  • Fr, Sep 12 2014 11:01 Antwort zu

    Re: Vespa gearing...


    Thanks for this.  I had guessed 20 tooth, but was a little confused working things out. The engine has a sito plus exhaust on it.  I am not  a lightweight either.  It runs OK most of the time, but up long slow hills it loses speed.  I just wanted to try down gearing it a little to see if the shorter gears helped it hold speed a little better.

     

    many thanks for the help

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  • Fr, Sep 12 2014 18:02 Antwort zu

    Re: Vespa gearing...


    you are welcome for the help.

     

    there is a nice helpful gearing section and p-series gearing calculator at www.scooterhelp.com ( http://www.scooterhelp.com/tuning/gearing.html ). other good scooter info there too.

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