how do I adjust a lawnmower carb to keep it from surging?
GW K asked:
I have an older Toro 2-cycle lawn mower with a Suzuki engine and a Mikuni carburetor. While idling, the speed surges and then comes back down. If I raise the speed it runs fine as it does while mowing. Is there an adjustment I can make so it idles evenly? Thanks.
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I have an older Toro 2-cycle lawn mower with a Suzuki engine and a Mikuni carburetor. While idling, the speed surges and then comes back down. If I raise the speed it runs fine as it does while mowing. Is there an adjustment I can make so it idles evenly? Thanks.
February 27th, 2009 at 5:01 am
turn the low speed adjusting screw in slowly until it starts running rough - then back it out slowy until it smoothes out and stop there.
March 2nd, 2009 at 10:30 am
If carb adjustment doesn’t work:
Look on the side of the carb and you will see a little plate with a spring connected to it. It moves with the speed of the fly wheel. It is designed to increase the speed of your idle if the flywheel slows down. The fins on the flywheel move air, which moves the plate, which speeds up or slows your idle.
If this spring is weak, the plate moves too freely, causing surging. It is a very easy replacement, and should be less than $5. It may not be moving at all, and that will cause the same problem. This mechanism is called the governor.
You will need the model and serial of the engine when you get a replacement, as these are made with different specs.