MOPED ARMY

Im trying to do some aux exhaust ports on a stock puch cylinder which I kinda got bored of after 5 min really id say stock cylinders are best to try aux ports cause you can always upgrade to a kit if you screw it up. Unless you have some mega rare stock cylinder. Most of the time I think that you can always have a bigger exhaust especially if you arent changing the port timing. The charge goes out the exhaust so yes the charge goes through them (assuming your talking about aux exh ports). I really havent seen people do these on 47mm puch cylinders I think cause the studs are too close, which is also why I think stockers are best. As for size you can always go bigger going smaller requires more work than everyone on MA would ever do.

There's heaps of info in JBOT's thread if you didn't check it out...

http://www.mopedarmy.com/forums/read.php?7,3550723,page=1

The nice thing about having 3 exhaust ports over one is that you do not need to have as many degrees of blow down because you have the width of the three ports to get the same flow before your transfer ports open

The other good thing about this is it you get more Low end power because the compression stroke is longer due to the fact that your exhaust Port is not as high to get the same flow as you would have with 1 exhaust

To get more low end power you will need to lower your exhaust port by some means. Just aux porting an existing cylinder has the effect of raising the exhaust port without actually having done so as the spirit of CW pointed out above and I try to make more clear to the neophyte.