Good morning Listees

Last night I installed new exhaust gaskets because the PO never put any on,
It always ran fine just sounded bad. Now it sounds quiet. This morning I was
on the way to work and it was running very rich then after I turn it off I
could not get the engine to start. My question is where do I adjust the air
to fuel so the engine will lean out? and where is a good starting point?

Darren