I have a Snapper 5HP Quantum XM mower with oil leaking from the muffler. Also, there is smoke when it is running.
Does anyone have any ideas on what the problem could be and how I can fix it?
Thanks!
Robert

Worn piston rings and possibly a worn block.
 
Remove head, check for a wear ridge on the top edge of the cylinder. 
 
If not too bad, remove piston to access worn rings...
 
Also note, not related to your issue, that the 3 head bolts, closest to the exhaust OFTEN LOOSEN UP
and cause running issues and leaks..
 
.

I am experiencing leakage on this mower from the breather tube. 
The mower is a Yard Machines 20" with a 300e/125cc Briggs & Stratton
engine. I replaced the breather reed, thinking that might resolve
the issue, needless to say it didn't. 
Any suggestions?
 
 
 

Worn piston rings and possibly a worn block.
 
Remove head, check for a wear ridge on the top edge of the cylinder. 
 
If not too bad, remove piston to access worn rings...
 
Also note, not related to your issue, that the 3 head bolts, closest to the exhaust OFTEN LOOSEN UP
and cause running issues and leaks..

Thank you.