7.4 Weak output or change of speed
There are no sparks at the spark plug
Symptom/Category
Cause
Solution
Compression is good
and there is no flame
out.
Air has gone through the fuel pipe joint.
Make sure it is tight.
Air has gone into the fuel pipe because of a
crack or pin hole.
Replace.
Air has gone through the pulse pipe.
Make sure it is tight.
Air has gone through the insulator and carbu-
retor installation part.
Replace or tighten the gasket.
Air has gone through the oil seal.
Replace.
There is water in the fuel.
Empty and clean the tank, then fill with good
quality fuel.
The piston is burned.
Remove the burn with a file, or replace.
Carbon blockage in the muffler.
Clean.
Overheating.
The engine is running lean.
Repair or replace the carburetor.
Blockage because of dirt in the air channel for
decreasing temperature.
Clean.
Blockage because of dirt on the cylinder fin.
Clean.
Low quality fuel is being used.
Replace with good quality fuel.
The level of carbon has increased in the com-
bustion chamber.
Clean.
The spark plug tip is red hot.
Champion RCJ 6Y/NGK BPMR 7A: Adjust to
0.5 mm.
Other.
The air filter is too dirty.
Replace the air filter.
Too high load.
Lower the load.
7.5 Other engine problems
There are no sparks at the spark plug
Problem
Cause
Solution
When the engine rev-
olution decreases, the
blade does not stop.
The clutch spring is broken.
Replace the clutch spring of the engine.
The clutch is open because of rusty clutch
bolts.
Remove corrosion from clutch bolts, apply
grease and assemble.
When the engine rev-
olution increases, the
blade does not rotate.
The drum bearing does not move.
Replace.
Strong vibration.
The blade not balanced.
Install a new blade. Make sure that the right
bushing is used.
The vibration dampening element is broken.
Replace.
72 - Troubleshooting
1451 - 001 - 02.04.2020