I had a friend ride his jawa with no exhaust whatsoever, it fried the exhaust port, all carboned up etc, a hot spot is where some exhaust gas escapes rather than being sucked into the pipe, it raises the temp around the area of the leak, can cause damage/ carbon build up etc all in all not a good thing. Use a new crush gasket if your bike has them when you reseat the exhaust to the jugg. Best of luck!