The reason why the power of the brush cutter decreases after use

The reason why the power of the brush cutter decreases after use 

I. Air intake system blockage (most common)

Air filter clogging

Weeds, dust, and grass debris clog the filter, resulting in insufficient air intake, excessive mixture, sharp reduction in power, unstable idle, and prone to stalling.

Solution: Remove the filter, clean with a sponge and dry it, then apply a small amount of engine oil; for paper filters, replace directly. Clean once every 1-2 days.

Air intake pipe and throttle jamming

The throttle cannot fully open and remains partially closed, restricting air intake.

Solution: Check if the throttle lever and pull wire are stuck, reset to the fully open position, and clean the accumulated dirt.

II. Oil circuit faults

Fuel filter / oil pipe clogging

Long-term use of impurities clog the filter and oil pipe, resulting in poor oil supply, insufficient power under heavy load, and inability to reach the required speed.

Solution: Replace the fuel filter and clear / replace the oil pipe if it is aged; regularly drain the sediment at the bottom of the fuel tank.

Carbon deposits in the carburetor and oil passage

Grease and gum block the main metering hole and idle hole, resulting in insufficient oil supply, more significant power reduction after warm-up.

Solution: Disassemble and clean the carburetor; do not store fuel for a long time; use fresh and qualified fuel as much as possible.

Incorrect fuel ratio (for two-stroke engines)

Too much engine oil ratio, insufficient combustion, poor power, excessive smoke, and more carbon deposits.

Solution: Strictly follow the engine model ratio (typically 25:1/50:1) to mix the fuel.

III. Ignition system abnormalities

Carbon deposits on spark plugs, abnormal gap, and aging

Carbon deposits from combustion cause leakage, weak ignition, insufficient power, inability to increase speed.

Solution: Remove and clean the carbon deposits, adjust the electrode gap (0.6-0.8mm); replace if the electrodes are severely worn.

High-voltage pack / high-voltage wire leakage

High temperature and vibration cause insulation layer damage, resulting in reduced ignition energy, decreased power under load.

Solution: Check the wiring insulation layer; replace if damaged.

IV. Exhaust system blockage

Carbon deposits in muffler / exhaust outlet

Remaining carbon deposits from combustion block the exhaust passage, preventing exhaust from being discharged, causing engine憋force， inability to reach the required speed， and accompanied by noisy and muffled sounds.

Solution： Remove the muffler and clean the carbon deposits； if the blockage is severe， drill to clear； replace if damaged or worn.

V. Mechanical transmission and body faults

Excessive resistance of the blade

The blade is tangled with long grass， dirt， or the blade is deformed， bearing wear， or bearing jamming， resulting in a significant increase in load， and obvious "feeling of weakness and inability to cut grass".

Solution： Stop the machine to clear the tangled debris； adjust the blade and apply lubricating grease to the bearings.

Slippage of clutch (for side-mounted / backpack-type lawn mowers)

Clutch shoe wear， oil contamination， unable to fully engage at high speed， and power not reaching the blade.

Solution： Clean the clutch disc of oil contamination， replace the clutch shoe if severely worn.

Cylinder block and piston wear

Long-term lack of maintenance and high-temperature operation result in insufficient cylinder pressure， continuous weak power of the entire machine， accompanied by blue smoke and abnormal noise.

Solution： Need to disassemble and inspect， replace piston rings， cylinder liners， and other components.

VI. Other causes

Engine overheating

The radiator is covered with grass debris and dirt， resulting in poor heat dissipation， triggering power limitations under high temperature， and becoming weaker over time.

Solution： Stop the machine to cool down， thoroughly clean the radiator and engine casing debris.

Loose / stuck throttle pull wire

Unable to pull the throttle to the maximum position， the throttle cannot fully open， and output power is limited.

Solution： Adjust the pull wire tightness， lubricate the moving parts， replace the pull wire if severely stuck.