Suzuki LT-Z90 Manual page 226

7-4 SERVICING INFORMATION
ENGINE RUNS POORLY IN HIGH SPEED RANGE
Symptom, possible causes and remedy
• Weakened valve springs.
• Worn camshaft.
• Valve timing out of adjustment.
• Too narrow spark plug gap.
• Ignition not advanced sufficiently due to poorly
working timing advance circuit.
• Defective CDI unit.
• Defective ignition coil.
• Defective generator coil.
• Low float chamber fuel level.
• Clogged fuel hose, resulting in inadequate fuel
supply to the carburetor.
• Clogged fuel valve.
• Clogged air cleaner element.
• Sucking air from carburetor joint.
Replace.
Replace.
Adjust.
Adjust.
Replace.
Replace.
Replace.
Replace.
Adjust float height.
Clean and prime.
Clean.
Clean or replace.
Repair or replace.