JAP 2A Exhaust

On the JAP 2A engine is the exhaust mushroom an interference fit onto the exhaust stub or threaded. Mine appears totally solid can anybody offer advice as to how to get it off. I have tried limited brute force without success.

I think the silencer and stub that screws into the block are all one piece and sold like that, mine seem to be?

Pete.

Many thanks. Now that I know what I am doing the application of a large Stilson wrench and a long lever has had the desired result. I had assumed the the mushroom can off the stub and not that they were a single piece. Many thanks.