Downpipes.. Old ones off - cant get new Motad ones on

[Dead Eye]

make sure you have completely cleaned the exhaust port where the copper gaskets sit, I held my new copper gaskets in will a little exhaust paste,
a little bit of fiddling and the pipes lined up, the only issue I had was the where the exhaust went under the engine the centre stand fouled them when being raised and lowered, I ground a little bit (1-2 mm off the stand where it rubbed, job done

I used petroleum jelly (Vaseline) to hold the gaskets in place. Since its petroleum based any excess will just be burnt off and the rest gets baked and creates a good seal No trouble removing them after this either (which I've had to do). Wouldn't exhaust paste eventually break down in to a grit / powder?