Why would the 21 hp Briggs and Stratton engine on your Husqvarna riding mower seem to have power surges when mowing - oil is fine and air filter is clean choke seems sensitive?

Answer 1

When you say power surges, are you referring to the engines surging, or the equipment jerking? If its the engine doing so, then chances are you have debris in your carb, coming from stale or old fuel, or even moisture. Before cleaning the carb, check for intake manifold air leaks; make sure connections are tight. Air leaks can also cause surging. Next thing is look for a mixture screw. If you find one, richen the mixture about 1/4 turn at a time. If a full turn doesn't help, then you've got to remove and clean the carb.

If its the equipment does it, the jerk I mean, after the machine gets warm, idlers that have bearings going bad can do that, or a belt stretching will do so. If its the belt though, don't be cheap. Don't go buy a car belt thinking they are the same, they aren't..lawnmower belts use Kevlar or thermmoid, because they go thru shock load, because of the start and stop; automobiles don't...lawnmower belts cost more, but are worth it..