Cure for Briggs 120000 series 'hunting'
Briggs 121312/0144/031230, this engine was the topic of a recent post on carb problems. Thanks again for all the good input allowing me to fix it!!!!
These engines have a tendency to hunt, I've read it on other forums, have a couple of neighbors who have them on tillers, and it's pretty much agreed that they do. I recall commenting that I thought this was due to Briggs putting the wrong governor spring on them.
This is a photo of the governor linkage on my tiller. If you look closely, you'll see that the governor spring is wrapped around the governor rod the entire length of the rod, and it's a relatively tight fit. The Briggs IPL shows this assembly as "632" which is further defined as "spring/link" Mechanical Governor and is manufactured and sold as a complete unit.
OK, engines have a tendency to acquire a coating of oil/dust while in operation. This engine is on a tiller which is a particularly dusty environment. Admittedly I hadn't examined this, and assumed that the governor spring was back under the cowling somewhere. What I found was that the spring and rod had acquired a good coating of oil and dust and were essentially stuck together so only one or two coils at the carb end of the spring would flex. Sprayed it really well with carb cleaner then blew it out with air. This broke everything free and now it no longer hunts.
I'm not sure of any lubricant or cleaner which would successfully address this as the oil and dust would continually be deposited while in operation. Evidently if you don't want your engine to hunt, periodic cleaning as i did is required.