FrankenPuch: Building an Aluminum Puch Moped

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Complete bike!
Goal: re-imagine a 1980's era Austrian Puch with a handmade aluminum frame, rebuilt engine, and custom seat

Materials:
  • Old "donor" Puch from Craigslist (non functional)
  • New piston, cylinder, clutch, and bearings for motor (sourced locally from treatland.tv and Bearing Agency)
  • Lots of 5"x3" 1/8" wall aluminum rectangular tubing
  • Other aluminum bits (head tube, 1/8" sheet for motor mounts, etc.)
  • New front forks, handle grips, exhaust pipe

Processes:
  • Frame layout and TIG Welding
  • Machining (basic lathe and mill work)
  • Engine rebuild and tuning

the process

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Seat tube and fender assembly.
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Making sure the engine fits.
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Transmission guts. This entire chamber is flooded with oil when in use.
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A new piston and cylinder kit was installed, increasing the engine's displacement from 50cc to 70cc and bumping its HP up to a whopping ~4HP.
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Beginnings of seat tube assembly. The difficulty of welding aluminum was more than made up for by the ease of cutting and shaping it.
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I became pretty good at TIG welding aluminum.
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The shift "pucks" absorb the impact inherent in shifting from 1st to 2nd gear under load. The 1980's vintage ones (right) were looking pretty crusty, so I took the opportunity to replace them with ones cut from a more supple, temperature and oil resistant rubber (left).
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Completely rebuilt ZA-50 2-stroke, 2-speed engine.
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I still don't have a bandsaw... got plenty of exercise!
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Stator side. Old timing "points" were giving me problems, so I replaced them and re-adjusted engine timing through trial and error.