Originally Posted by BUBB
let's start slowly....
first of all is that a two or four stroke?
Occasionally a 3 or 4 stroke.
The bike is a licensed-built Vespa PX-150 which was built in the late 70's and 80's using state-of-the-art 50's technology.
It's a 2 stroke motor and manual 4-speed transmission. Stock, they are quite reliable and peppy.
This is generally what the classic Vespa 2 stroke drivetrain looks like from the left side:
You're looking at the swingarm and rear drum brake and cylinder.
Here's the right side view of a vintage vespa engine:
That's the kick starter hanging out there.
The engine is air cooled. The flywheel is also the fan, which forces air through a plastic cowl. The entire shebang sits underneath a fender cowl.
The clutch is cable actuated, as is the transmission. The original design came from the flap-actuator system off WWII aircraft. You shift by rotating the left hand grip as you squeeze the clutch.
The Stella uses a reed valve electric start 150cc engine that makes about 8 hp on a sunny day, 10 when it's really happy, 12 or so with a decent kit. If you want to sacrifice reliability, you can get 25+hp out of them...which will keep the front end in the air through the first 3 gears if not all 4.
While some people keep them stock and are happy, the rest of us tune 'em, which requires some skills with understanding how 2T motors work, as well as being pretty sharp with carb jetting. That's part of the allure.
Anyway--the older bikes like the Vespa (and Stella) and Lambretta with their manual transmissions are referred to as "classic" scoots, "shifties", "metal scoots" and all sorts of names (including "YOU POS") to differentiate them from the automatic scoots.
They are the Royal Enfields of the modern scooter lineup--a brand new old scooter that requires a lot of owner attention to get the best out of them, and therefore a bit of craziness at times.