Annoying Carb/Vespa

Discussion in 'Newbie Scooter Tuning' started by ORB, Oct 11, 2018.

  1. ORB

    ORB New Member

    Hi chaps

    I’m quite mechanically minded, worked on cars for years, but I’m relatively new to Scootering!

    I have my ped running like a dream, however my neighbours has been running like crap since he bought it a year ago.

    It’s a Vespa SX 50 2t on a 2011 reg.

    A brief history is, the bike was well used, left outside and quite probably badly maintained by its previous keeper. The exhaust was rotten and loads of the fixings were bad too, so we replaced the exhaust (like for like standard)

    It still ran crap, so we took the carb off, stripped it and cleaned it properly with carb cleaner and compressed air. Put it back together. Still runs crap. Probably more crap than prior!

    We took the brass destructor plate from the inlet off the carb too and chucked it while we were cleaning the carb. I was wondering if you could tell me the following:

    - Good base settings for the carb to tweak from

    - Do I need to upjet due to removing the brass plate thing?

    - the auto choke always makes it run worse, so we replaced that, still no better. It’s better when unplugged - why and what to do? (It activates as it should as I’ve bench tested)

    The behaviour of the bike at the moment is such: starts fine, ticks over. Quite smokey, but nothing much more than any 2t engine. Hit the throttle, bike sets off then looses power, won’t rev and dies off. It’s never been that bad before. He nursed it home last night not being able to get over 15mph.

    I had a quick play with the mixture screw last night but I’ve a feeling there may be more to it?

    Thanks in advance for your help!
  2. 4strokelover

    4strokelover Active Member

    Longjia Raptor 200
    I have no idea about your problem but mine ran better without the autochoke so i took it off. Dont think its recomended but its done now aha.
    Hopefully someone else more helpful will come on and help you.
  3. ORB

    ORB New Member

    Well, I worked it out for myself.

    Since removing the Brass plate from the carb mouth was letting more air in, I figured I should lift the needle a notch too. It worked.
  4. MARSH

    MARSH Whooooo!

    Piaggio Typhoon
    A bigger main jet will help.

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