Originally Posted by 2door
This tells you the exhaust manifold gasket is leaking. Remove the exhaust pipe/muffler and clean the gasket surfaces well. Check that the surfaces are flat by sanding lightly with a block of wood or metal wrapped with sandpaper. Gasket material is available from auto parts stores in sheets. You can make your own gasket. I've found that a gasket about 1/8th" thick works well. I'm not a fan of studs and nuts so I replace them with Allen head cap screws. If you have a 2 stroke engine the bolts will be 6mmX1 thread and about 20mm long if you use the thicker gasket. Good luck. Let us know how you make out.
What gasket material do you use? Is there one made specifically for exhaust?