Change engine oil, clean oil screen, check valve clearance, retorque head nuts.
Disconnect the black/white wire from the CDI module harness. This eliminates the kill switch loop. Check for spark again. If spark returns, your kill switch, ignition key switch, or wiring harness is shorted to ground. Stator Component Testing (Using a Multimeter set to Ohms):
Reinstall the components in reverse order. Ensure the float needle seats smoothly. Idle and Mixture Tuning 152fmh engine service manual
Turn the square adjuster screw until the feeler gauge slides through with a slight, smooth drag.
Place a drain pan under the engine. Remove the drain plug located on the bottom-left side of the engine case. Do not mistake the angled timing chain tensioner bolt for the drain plug. Change engine oil, clean oil screen, check valve
Before turning a wrench, verify your engine code. The code is typically stamped into the lower left side of the crankcase, near the gear shifter. Decoding the 152FMH Engine Code 1 : Single cylinder 52 : 52.4mm cylinder bore F : Natural air cooling M : Motorcycle/powersports application H : 110cc displacement class Technical Specifications Specification Engine Type 4-Stroke, Single Cylinder, Air-Cooled, OHC Displacement 107cc (commonly marketed as 110cc) Bore x Stroke 52.4mm x 49.5mm Compression Ratio 9.0:1 to 9.7:1 Idle Speed 1500 RPM ± 100 RPM Spark Plug NGK C7HSA or Torch A7TC Spark Plug Gap 0.6mm – 0.7mm (0.024" – 0.028") Cooling System Forced Air Cooled Ignition Type CDI (Capacitor Discharge Ignition) 2. Fluid Capacities & Torque Specifications
Avoid "Haynes" or "Clymer" manuals that cover 1970-1990 Honda bikes. While helpful, they miss the electric starter and CDI specific to the modern 152FMH. Check for spark again
If your engine loses spark, test the components in this specific sequence using a digital multimeter set to resistance (Ohms): Swap with a known working NGK C7HSA plug.
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 replica motorcycles (such as Honda Trail or Cub clones), this 110cc-class four-stroke powerhouse is prized for its simplicity and durability.
Check valve clearance; inspect piston rings and cylinder walls. Incorrect air/fuel mixture