Cub Cade riding mower. 24 Hp Briggs & Stratton V-twin engine. 129 Hours, 6
years old.

SWMBO has been complaining that it doesn't have the power that it used to
and it kind of 'sputters'.

Put on new air filter (really needed it) and pulled the plugs. Left side
plug is sooty (black) compression is 72 p.s.i. Right side plug is normal
(light brown) but compression is only 40 p.s.i.
BTW, both plugs were very clean, i.e., not crusted or worn. Plug gap is
right on the money.

Upon buying this riding mower 6 years ago (we're new to country living) my
neighbor said "nice machine, you'll be buying one every 5 years". I hope
he's wrong.

What could be going on with this engine? Is 129 hours a lot?

I've rebuilt probably 15 car engines over the years. I've done 2 automatic
transmissions. Have never tackled a 'small engine'. What do I need to
know? Do I inject a little oil, redo compression in order to differentiate
between piston ring wear vs. valves?

All directions and encouragement would be greatly appreciated. I don't have
the $2k± to go buy a new one.

Help!!

Ivan Vegvary