Exhaust restriction

[Matthewd73]

Any help on this matter would be appreciated. I have been rebuilding a 400 chief over the last few months and finally got it fired up. After getting it fired i put the exhaust header on to connect the motor and muffler. As soon as i did the motor died down fairly drasticly. I figured there was a restriction in the muffler so i ended up cutting both ends of the muffler off to clean it out but i could not get to the baffles in the middle. I cleaned it the best i could, let it soak in muratic acid and heated it in a burn barrel to get anything out. I welded it back together and put it back on and it is still doing the same thing. I was curious if there is something still inside in the baffles blocking it or if they are designed to have some restriction. I can get it to idle if i turn the idle screw up but it seems like the motor keeps loading up. Any help would be appreciated, thanks.
-Matt

[6X6]

Hi:
2-Strokes are more sensitive to back-pressure than 4 strokes. If your muffler is plugged, you won't be able to get a lot of revs under load. I think you just have to tune the carboretor, or adjust the idle. If you change the back pressure in any way, it will change how the engine runs at any speed. The mufflers on these engines are to quiet them down, but they don't help performance, thats for sure. But you can't run it without any pipe, (or just with a header) that's no good either.

OK, some info.
This is why you hear about tuned pipes. Without going into all the different aspects of them (And theres a LOT more to them than most people realize) the tuned pipe provides the right amount of backpressure, and in sync with the engines pressure pulses. Since a two stroke has the exaust port open the whole time the intake is open some of the fresh fuel charge is pushed out the exaust with the exaust gasses. Since the vast majority of this waste follows after the spent gasses, the tuned pipe's job is to provide a positive pressure pulse (Backpressure) to force this back into the closing exaust port. This increases the fuel/air charge in the combustion chamber. But it must be timed just right. To soon and it will prevent the exaust from properly escaping and power is lost and if severe, overheating can occur, to late and much of the fresh charge will get back after the exaust port is closed and power/fuel economy is lost. Pipes are tuned for, among other things, a certain RPM range. If you do a lot of low speed running, you would want a longer pipe/header setup, as the lower RPM lends itself to longer pulses and you want that pulse to take a little longer to get back or it will be too early. But your engine will not rev with as much power as the pulse will be getting back later and later as you do. High RPM requires a shorter pipe, as you need the pulse to get back quicker, but it will be early at lower RPMs, so you don't get the same low-end. The angle the pipe opens up (Divergent Cone) angle it tapers back down again (Convergent Cone) the length between the two (Belly) as well as the length and diamiter of the stinger or exaust tip all can greatly influence how a pipe operates. Compramises are made for good mid-range, but top and bottom end just aren't the same as with a top or bottom end pipe. Now that that's out of the way, does anyone make tuned pipes for the JLO singles and twins? I know I have seen them on the springer racers, but are there any that can go on a more or less stock Attex?