This mower lost a exhaust valve into the cylinder due to the retainer wearing out. Got it put back together and it starts and runs ok, but it looses power after it mows awhile and will not start till it cools down. I was wondering if the flywheel key might be partly sheared. Just asking before I...
Briggs Stratton engine model 4P90HU 420CC exhaust valve retainer wore out and let valve go into the cylinder. The valve is bent, cylinder is ok. Is any one else having this type of trouble with the valve retainers. Engine only has 24.7 hr's on it.