building a high performance 50cc engine
 

http://www.scootdawg.net/picture.php...&pictureid=631http://www.scootdawg.net/picture.php...&pictureid=635My current project is a qmb 139 engine that has over 5k miles on it. It has received a 42.5mm stroker crank, 52mm hoca bbk with specially modified piston, Hoca 52mm bore big valve head, gy6 polished aluminum intake manifold, and a custom camshaft totaling roughly 96 actual ccs currently staying at 10.5 compression ratio. The gearbox has been regeared with 2.411 gears for more top speed potential from scrappy dog scooters,

Future modifications to be installed will be an 11 coil stator conversion from NYCscooterparts.com, a modified efi conversion from ecotrons.com, a custom 1.25 in stainless steel header with oxygen sensor bung installed manufactured by a local company right here in the USA with oxygen sensor bung installed, and custom head porting and polishing by another local company.

Various parts have been purchased from companies to include scrappydogscooters.com, NYCscooterparts.com, partsforscooters.com, buggydepot.com, ecotrons.com, scoot-tuning.com and a few others

Very nice! How does she run now?

You know that intake side should never be polished right? Only the exhaust side needs to be like that :)