How can I modify the stock Motobecane 7 exhaust for a 70cc Parmakit / Lost back plate

Dan Kubica /
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I lost the back plate of the exhaust of my 1978 Motobecane 7. Well, actually, I did find it, but it was crushed. All I could saved was the tube.

I noticed the "header" inside the stock exhaust looks like the one 1977 sells basically. I have a 70cc Parmakit and Dellorto 15.15. Is there a way to maybe cut out the header and put a beer can baffle on it? Or anyway to fix/modify my stock exhaust so that I have enough back pressure, but I am not totally restricting it without access to the back plate?

I rigged a fix up, but it is quite ugly and has leaks. Basically just sheet metal with a hole drilled in it. The motor backfires and gets hot, so it doesn't work. Would it be easier to just get the straight header out of the stock exhaust and restrict it somehow?

If anyone has tried anything like this or has a good idea on what can replace the back pressure when the stock back plate is no more, please help.

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