DIY exhaust for pre-88 2pg? No expansion chamber?

[ezneel]

Am I wrong with assuming that they did not utilize any kind of "expansion chamber" style exhaust on these things? I think my muffler is plugged up, I am BBQing right now but I havent got flames out the end yet, so Ill probably cut it open and see what is going on. Either way, I bought this cart not running with a blown cylinder base gasket, no idea why it was, but I pulled the motor, new gaskets, cleaned the carbon off everything, honed and re-ringed it. I have 100 psi compression, which I know is not awesome, but it should run....but I can't get it run with the muffler on, but I can get it to run with it off....(holy crap is that loud, don't do that, lol). Anyway, I know from doing some research that the 88 only exhaust was a different setup a gained a little power with the help of the bigger carb. the muffler looks larger in the pic and it sounds like the head pipe is a little bigger? Anyone know how much? Point is, if my muffler is trashed, instead of re-packing it, I am thinking about just making a new head pipe that does a 90 out of the head and turns back, just under the rear suspension to a universal glass pack style muffler of some kind. I was planning on getting the larger carb as well anyway. The million dollar question is, am I wrong assuming that these do not have any kind of "expansion chamber" and if I go to a one size larger pipe to a more free flowing muffler, I may duplicate kinda what they did with the 88 exhaust? I really don't see what they changed besides making the head pipe and muffler a little bigger.... thoughts?

[clr.R4tch3t]

I don't believe they put any expansion chamber in the muffler. Having ridden 2-strokes my whole life (and still have 4 in the garage) I know the important role of the expansion chamber to 'supercharge' the intake. I am gong to try and fab up a 250cc fatty pipe I have laying around to it to see if it does anything. I live at a relatively high altitude (8150'), and my cart was also purchased in a non running condition, so I am not sure what these things are supposed to be able to do. Right now it wont get out of its own way unless it is headed down hill. I guess we will see what happens when I throw a pipe on it.