I posted this a long time ago, but was too lazy to find it.
While you are "port matching" and doing all these other things to try to make your chinese two stroke a "fire breather" (lol!) You will want to check the tip or outlet of the exhaust.
I have found a few that were welded nearly closed when they welded on the "stinger" or outlet pipe. All the port matching and nitrous/"high performance" carbs (again lol) ect. aren't going to do anything if the outlet is welded in there and the weld has closed all but a hole the size of a pencil.
I'm wondering if it can get clogged up somehow? Is it possible that some of the packing material inside one of these could partially clog a pipe and make it just not rev up like it should? I noticed around the bottom of my muffler some oil residue and the performance has been not up to par the past 40 miles or so. Should I drill a new hole in the bottom of the muffler next to the "real tail pipe"???
Brian in Everett, WA www.pdq-signs.com
BMW R1100RT, bunch of Hondas, Schwinn Sierra w/80-66 (Screamin Ninja Urban Assault Bike ;-) Iron Butt Association