Small Engines (Lawn Mowers, etc.): High reving push mower, centrifical clutch, handelbars

Question
Hi Matt,

Thanks for taking the time to answer this question.  I have a push mower that has been reving high.  It almost sounds like the engine is running at full capacity.  When I start it, it sounds normal, but within seconds, it begins reving higher and higher.  After a few seconds of high rev, it cuts out and returns to normal and begins the cycle again.  This happens continuously the whole time I am mowing. (normal - high... normal - high... etc)  I had it to the shop about a year ago, and it seemed to be fixed for a little while, but now it is happening again.  I dont want to take it to the shop again.  Do you think this is something that I could fix myself?

Thanks again,

Daniel

Answer
My first guess would be that the govener has loosend and slipped. From the throttle plate on top of the carb there is a piece of wire linkage that runs to an arm attached to a small stem sticking out of the side of the engine block. this stem runs inside the engine and rests against a centrifical clutch as the engine revs up the clutch pushes against the stem paddle and pushes the throttle back to a slower speed. This is easy to fix you dont have to take anything apart. Find where the linkage arm attaches to the govener stem coming out of the side of the engine its held on with a 3/8 inch nut or a screw, loosen the nut just enough so that you can turn the end of the stem with a pair of pliers it may not feel like it even moved at all but it only has to have slipped just a tiny bit. You are going to turn the stem towards the carb. In other words if you are standing behind the handelbars of your mower and the carb is on your left you will be twisting the stem counterclockwise if the carb is on the right hand side then you will be twisting the stem clockwise. while holding the stem as far as it will go in the direction towards the carb then tighten the linkage arm back up and give your mower a try. i hope this makes sense its so much easier to do than explain. basically what you are doing is adjusting everything towards high speed and taking out the gap between the clutch and paddle inside the engine