Nick,I don't know Puchs too well,but I get the feeling maybe you've got the wrong piston kit?Some PUCH gurus out there will maybe give you some help.I've got a 2-speed Puch Maxi shop manual but it doesn't cover the speed kit.When you look at the stroke there shouldn't be a way for compression to escape once the intake ports are covered by the piston;I don't think so anyway.But man,if you've got the wrong piston and or jug you're fightin' a losin' battle!BYE!