I have a generac 4000xl generator model 09777-2 I bought in 2000, with a B&S engine Model GN220 and broke a valve spring retainer part a1720. It was replaced with a kit with springs, valves, valve spring retainer, oil seals, head gasket and the half clip retainers (Generac part # 0D24890ESV). My first question is, do I need to replace the whole kit or can I just replace the valve spring retainer washer and clips?
My second question is the retainer broke due to an overspeed condition. It happened after I took the carb off to clean it out. When I reinstalled it, I had the idle switch on and when I powered a drill, to check it out the engine started screaming (Over reving). I shut it off immediately avoiding any catastrophic outcome. I suspected the linkage going to the governor so I removed and reinstalled the carb making sure the linkage spring was installed what I was proper and thought I had fixed the problem as I powered my drill several times and it responded by raising the rpm’s and returned to idle when I released the trigger. As it turned out, I needed the generator the next week when I woke up to no power. Confident I fixed the problem, I stretched out a 100’ 12-3 cord, started up the generator and plugged my coffee pot. As soon as I powered it up the generator started to scream and before I could run outside to shut it off, it broke a valve spring retainer washer in half and the generator shut down.
When I cleaned out the carb, I did not touch any part of the governor, only the linkage that attached to the carb. What could cause the over revving condition.
I answered my first question myself. Upon looking at both valve stems, I realized that the new stems were designed for the new half keepers and not for the old style keepers. I had to pull the head, lap in the new valves, install the new stronger springs, spring washers and new retainers.
The pictures show the old then the new. After reassembling and making sure the linkage was installed correctly it appears to be working fine With no over speed condition. I ran it ten minutes using a fan turning it on and off and it responded perfectly coming down to idle when the fan was shut off and raising to running speed when turned back on. I repeated the test about two hours later when the generator cooled off. Again it ran perfect.
I posted my findings and results to benefit others that may run into this issue.
