That looks distressingly like the engine on an ancient 4 stroke rotary mower I bought (very) second-hand in about 1970. It was hard to start and didn't run very well, like yours - might be the horizontal version of the same engine (I never liked mine enough to remember what kind of engine it was. There was nothing wrong with it, but it ran like a POS. It even set fire to its own air cleaner once. I foolishly put it out - would have been more fun to watch it burn.) On yours, one of the governor springs seems to be trashed. It now thinks it's four different springs in series, each with different characteristics. It started life as a close-coiled spring, as the left-hand end of it still is, but somebody stretched it several times until it yielded severely. It won't work properly in that condition. It can be replaced by any close-coiled tension spring with the same free length and the same 'rate' - that is, how hard you have to pull to stretch it say one centimeter. Standard handyman stuff. BTW, you measure the free length by taking it off, squeezing it until it is close-coiled, and measuring the distance between the two end loops. Usually you can't get a spring the right length and you have to cut and reshape one end of a longer one. Meanwhile that crook spring could be causing all the problems you have described.
Edit: The engine in the pictures is a Kirby Lauson (Australian-made Tecumseh/Lauson).
Last edited by grumpy; 14/10/11 03:36 AM. Reason: Clarify engine type
