The port sizes for the exhaust and two transfers are passable.....but that intake is just a joke
. Most mopeds have a least twice the area and 15cc less displacement.
I opened the intake ports sides by 1.5mm a side and lowered the floor by 1.75mm. The inlet manifold was also machined to match the cylinder's mount, it orig was just a hole that didn't even come close to matching the cyl opening shape, bad for flow
The port is actually MUCH too high as cast, I've never seen a 2 stroke that has the port cast SO high up the cyl wall that at BDC the rings (BOTH!) are below the roof of the intake port. Chinese engineering is still a mystery
No way of solving THAT problem without casting up another (read BETTER) cylinder.
The exhaust port wasn't bad in shape BUT had very short timing, raised the roof 1.50mm and widened .5mm a side. Still in the mild tuned arena for sure but at least now the poor thing has a decent blowdown period.
The port mapping I used is near a Puch 50cc moped spec so it's not radical just better.
I also added some machining to the bushing type
rod end and am working on a very inexpensively modded pocketbike pipe, look for the new threads on those. A new 18-20mm carb is slated to be used here as well.
I have not run this particular cyl yet but because the specs are from exsisting engines that do perform well it should be good.