48cc porting advice

what will be the use of this engine? why you want to port it? some more specs will be very usefull...
most of the times porting is not the issue with cheap industrial china engines but really poor carb and exhaust.

don´t use those specs, they are not made for that kind on engine!!!! a 96atdc coupled with a simple box silencer will just kill the engine. not enough torque even to pull the flywheel wheight :laugh:

just to give you just one exemple i have a 30 years old casal boss 50cc, two speed, air cooled. a friend gave me the bike if i made it faster, that was the deal. the bike only runs 60 kph stock and was a good engine... after some porting, modded exhaust internals, modded air box and filter, ignition etc... etc... the bike goes at 90 kph.
great, unless we always start the bike on a way down because the of idle torque wasn´t good and we have to fan the clutch too much even if the bike only weighs some 50kg. after a big sprocket change the power was very usefull but the bike only does 75kph. funny, the bike can pull his top speed on a straight, way up or down.

my father "stole" me the small bike and still ride it every day on some very slow trails on summer and on roads in winter some 2km trips.

to resume, the porting is VERY dependent to the gearbox, bike and the use one give it. :cool:

the book that rich advise on the link i gave you is very good as a starter. it will enlight you on the very subject of intake porting and timings. it provides a table for suggested timings based on rpm target. is very cheap and will give hours or reading and lots of experiments to do... :cool:
my personal experience with piston ported inlet engines is that they affect a LOT the carburation!!! open a full millimeter on that engine will render it useless. will knock away the bottom and midrange completely to give just a bit more peak (maybe) and more over rev and even may not idle at all!

i´ve seen your link now, is that engine the one with one piece cylinder head/cylinder?
normally those engines are very poorly manufactured and a lot of hp is hidden only correcting the engines. check the air filter system and muffler as well.
if you don´t have a great insight to carb tuning (jetting) don´t touch the engine because most of the mods require jetting. and most of the times the carb don´t allow any tuning.
cut added tranfer ports are usually possible and result well.

i deduce that this is a project to learn other wise leave it alone. GET THE BOOK!!!!

You 2 know your on the same continent? Probably 10,000 miles apart though, or not? Helio, he likely has ALL the books! Vintage Bob