Automatic Project

Original Condition

This is a project I have been considering for a while and it is great to finally start a project for myself instead of buying fixer uppers to sell off once running. My wife would love a scooter for herself but she's just not interested in shifting all the time and kickstarting a bike multiple times when it is cold. Personally the geared part is what makes scooters so much fun for me, but each to their own.

The problem is she really likes the old style scooters and wouldn't really want a new style auto. So I started thinking and found that Vespa made a PK style automatic with a 125cc engine. Would it work to retrofit one in to an older frame?..Let's find out.

Here's a picture of a 1974 Vespa 90 project I picked up which will be the donor frame for the project. I wanted a frame with the USA style doors on both sides because I will be fitting a battery. The bike was methodically disassembled, bagged, and labeled by the 2nd owner in the late 80s and sat in the garage in pieces. It came with a lot of brand new parts for the proposed rebuild so I used the parts, built up the motor and sold it off on the BBS to finance the new motor. Other parts that I didn't need were also sold off (indicators, wiring loom, regulator, etc..).

The PK 125 Automatica was only produced for Europe so it is a little hard to find here in the USA. It is an ideal donor as it has all the features of a current automatic such an oil injection option, reed valve intake, electric start option, and at 125cc it should be able to keep up with traffic. I'm pretty sure it is a 12V system too. I don't yet know if standard small frame kits will fit this bike - we'll see.

My idea for the project is as follows:

  • Add the PK 125 automatic engine to the '74 Vespa frame, but make the bike look totally stock except for the pulley shroud which will stick out below the bodywork in the same area the fan shroud would on the original.
  • Provide a new electric start system using a PX electric start button under the right hand side switch block on the handlebars.
  • Add a new tank with fuel sender and oil tank or a separate oil tank.
  • Remove the old ugly indicators and install handlebar indicators rigged to the old switch.
  • Install a bigger battery for the electric start.
  • Add a glovebox with fuel gauge, oil warning light (I have an oil sending unit left over from my RZ350 rebuild) and a volt meter.
  • Rework the cables so that the front brake still operates the front, but the back brake will be operated by the previous clutch lever. Weld up the old floor hole for the rear brake pedal. Set up the levers so that either lever works the rear brake light and one must be held to start the bike.
  • Abandon the existing horn, but leave it in place. Add twin 12V DC horns hidden under the legshields.
  • Possibly add more power or at least a better exhaust than the standard motor has.
  • Change the lighting to 12V with a halogen in the front.
  • Paint the finished scooter once it has been dry built.

I hope to move quickly on the project, and I will update the pages as it progresses.

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