This is taken from a PDF file of a Puch service bulletin concerning horsepower upgrades on Puch models
Conversion from 1.5hp to 2hp
Change:
Intake manifold from 12mm to 14mm (part # 321 315 630 1)
Head gasket from 1.5 mm to none
Air filter -- remove large pipe including orifice and plug and replace it with small pipe (part # 349 115 073 1)
Main Jet from 50 to 56 (part # 362 115 009 1/56)
Throttle slide from #51 to #24 (part # 349 115 015 1/24)
Needle jet from 2.12 A to 2.22 (part # 349 115 008 1/22)
Exhaust pipe drill two holes 10mm in diameter (see links below for details)
Original PUCH Service Bulletin, 4/12/83
Derestricting a Puch Maxi exhaust
Luck of the draw got You stuck with a 1 HP bike? Don't fret! You'll also need a new cylinder, and some sprockets if it's a 1 HP ZA50 (they have taller internal gearing).
