Stander Maintenance Tips: Engine Power Loss

Engine power loss in stand-on mowers is a situation when your mower fails to deliver the expected horsepower when mowing or running. In this state, the speed of your stand-on mower reduces even when its acceleration is at maximum. Engaging blades might cause it to stop or drag.

This can be quite daunting especially if you don’t know the real cause of the problem. Here are some possible causes of engine power loss in stand-on mowers and their solutions

Using Wrong or Worn-out Spark Plugs

the purpose of a spark plug in an engine is to give the required spark (Fireball) needed to ignite or burn the compressed air-gas mixture in the combustion chamber that moves the pistons back and forth resulting into the rotary motion that ultimately makes the engine shaft to rotate thus powering the blades and the wheels of your stand-on mower.

When you use wrong or worn-out spark plugs, the spark delivered in the combustion chamber will not be enough to burn the compressed air-gas mixture in it. This reduces the rotary movement of the engine shaft resulting into engine power loss.

Your stand-on mower might run, perhaps even mow but its engine will not be performing the way it is expected to since some fuel in its combustion chamber is not receiving the spark that burns it. This is called incomplete combustion. Incomplete combustion causes engine power loss.


  • Check the condition of your spark plugs
  • Use spark plugs that are recommended by the manufacturer.
  • Consider replacing your spark plugs in case your horsepower does not increase even after cleaning and re gaping.

Faulty or Broken Ignition Coils

This may arise when either the wire connecting the ignition coil to the spark plug is broken or the ignition coil itself is faulty. In this condition, the spark plug does not receive the needed electricity to create the bolt that ignites or burns the compressed air-gas mixture in the combustion chamber.

This leaves your engine relying on one spark plug and one piston to rotate the entire engine’s shaft which leads to engine power loss.


  • Use a multimeter to see if there is any broken wire in your ignition coils.
  • While your engine is on, unplug one of the wires connecting the ignition coil to the spark plug and see if your engine stops running.
  • You may swap the ignition coils and unplug the wires connecting them to the spark plugs one at a time while observing your engine’s response.
  • Replace the ignition coils.

Faulty Valves

This may happen in four instances, first, when the bolt holding either the bracket that supports the intake rocker arm or the bolt holding the bracket that supports the exhaust rocker arm loosens because of vibration. In either of these ways, the bracket ends up breaking the lag that holds it in its place.

  • The rocker arm then moves from its place and fails to push the valve (Intake or exhaust) which results in a failed combustion which results in engine power loss.
  • The second instance is when, either the intake valve or exhaust valve overheat and create carbon which hinders them from moving their full length in and out. This results in insufficient compression which also leads to a failed combustion hence, engine power loss in your Wright Stander Mower.
  • The third instance is when one of the push rods that presses the valves breaks and fails to either compress the air-gas mixture in the combustion chamber (intake valve push rod.) or fails to take out the exhaust gasses (exhaust valve push rod.)
  • Enlarged valve clearances between the rocker arms and the valve stem ends ( Check your owners manual to see the recommended clearance range.)

In all these four instances, there will be either a failed combustion which leaves the engine of your stand-on mower running on one cylinder head or the valves are not reaching their expected compression. In either way, there will be engine power loss.


  • Open the case rocker (The OHV valve cover on your engine.) and check the condition of the valves.
  • Include tightening the bolt that holds the rocker arm brackets in your routine maintenance.
  • Replace the broken push rod.
  • In case of severe damage, you may have to replace the entire cylinder head.

If you take the steps mentioned above, your stand-on mower should definitely regain its horsepower but if the problem persists, then, you may consider taking it to the mechanic.

Usually, engine power loss is caused by problems with the air compression and exhaust system this may happen due to wrong or worn-out spark plugs, faulty or broken ignition coils, faulty valves or broken pushrods. When you trace, find, and address these issues, stand-on mowers usually regain their power.

Doing maintenance tasks like these by yourself might help you address major issues before they emerge and even help you save a lot of funds that you would spend on hiring a specialist.

Those are some tips, try them out in case your stand-on mower loses its engine power. Let’s hear from you how your maintenance is faring. Wish you the best results as you start your path of getting the best out of your Wright Stander Mower.

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