Separating muffler from exh pipe

Good evening all. I need to replace the mufflers on a '75 E-Start due to a large crack in timing side unit. Anyone with a good tip on separating the muffler from the exhaust pipe without destroying the connection end of the muffler, and more importantly, the tailpipe end. Not worried about the broken muffler, I can cut it off, but would like to save the other one from a similar fate, if possible. The clamps came off easily, and I've pried the slit portions of the muffler away from the pipe slightly and have been spraying penetrating oil up there nightly for two nights. I've tried to beat the broken one off with a muffler chisel but it won't budge. Tried heat from a blower gun as used to peel wallpaper, no dice.
Any advice appreciated.
Best regards,

Mike Pappas
Northern New England Norton Owners

Hi Mike,

This works once in a while. Heat up the muffler with a propane or butane torch. Heat evenly all around (paint stripper guns or hair dryers aren't hot enough).

Now take a can of your basic electronics store freeze mist or freeze spray used to test IC chips. Sray this on the header portion about 1" away from the muffler clamp. Spray all around quickly all the time banging on the pipes with your free 3rd hand :shock:

The theory is that the cold pipe will contract inside the hotter muffler and break the rusted fused areas away from each other. Worth a try. Works about half the time for me (disclaimer).