Turn the air/fuel mixture screw slowly clockwise until the engine begins to stumble.
Before turning a wrench, it is vital to have the correct factory specifications. Using incorrect torque values can strip threads in the soft aluminum casings or cause catastrophic engine failure. General Specifications
The 152FMH utilizes a simple, self-contained AC-CDI system. The engine can run completely independent of a battery if it uses a kick-starter. Component Stator Resistance Values (At 20°C / 68°F)
Indicates an overly rich fuel-to-air mixture. Clean the air filter, adjust the carburetor float height, or drop the carburetor needle clip position. Clutch Slipping (Semi-Automatic or Manual) 152fmh engine service manual
Wet multi-plate (Automatic centrifugal or manual) Starter: Kick start and/or Electric top/bottom mount 2. Fluid and Lubrication System
Remove the screws securing the float bowl. Pull the float pin to remove the float and the fuel inlet needle.
The 152FMH is one of the most reliable and widely produced horizontal single-cylinder engines in the world. Commonly found in pit bikes, ATVs, dirt bikes, and super cubs ranging from 100cc to 125cc (often branded by Lifan, Loncin, Zongshen, and Shineray), this four-stroke, air-cooled workhorse is praised for its simplicity. Turn the air/fuel mixture screw slowly clockwise until
Remove the two large valve inspection caps on the top and bottom of the cylinder head. Remove the timing inspection plugs on the left crankcase stator cover.
[Cylinder Head] ---> Contains Valves, Camshaft & Rocker Arms | [Cylinder Body] ---> Houses Piston & Rings (52.4mm Bore) | [Crankcase Base] ---> Houses Crankshaft & Connecting Rod Disassembly Sequence
Remove one piston pin circlip using needle-nosed pliers, push the wrist pin out, and lift the piston clear of the connecting rod. Component Inspection and Reassembly Clean the air filter, adjust the carburetor float
Improper valve clearances lead to hard starting, loss of compression, excessive engine noise, or burnt valves. Perform this adjustment only when the engine is (below 35°C / 95°F). Specification Intake Valve Clearance: 0.05 mm (0.002 inches) Exhaust Valve Clearance: 0.05 mm (0.002 inches) Step-by-Step Valve Adjustment
Re-check the clearance after tightening to ensure the screw did not move. Reinstall the tappet covers and inspection caps. 5. Fuel System and Carburetor Tuning
If stator outputs are correct but no voltage reaches the ignition coil, replace the CDI module. 7. Troubleshooting Common Mechanical Symptoms Potential Root Cause Corrective Action Engine will not start (Has Spark/Fuel) Zero valve clearance; low compression.