All OHV Single cylinder motors are at risk for failure.
#1 Retainers fail due to poor design. Old or new style they are all junk.
#2 OEM Valves Brake off sending parts where they don't belong.
I do a complete head service were you send me a bare head and I fill it with Stainless Steel Valves and New Springs and new HD Retainers and HD Keepers too.
I shave the head and port the head too.
It is all cleaned up and ready to go back on.
I do this work or I sell the Retainers and Keepers.
But I don't sell the Valves so don't ask since there is a bit of work to get them in.
Call 701-400-4084 for Mower Info.
Don
