152fmh | Engine Service Manual
The 152FMH is a widely used 110cc horizontal single-cylinder engine, typically found in Chinese-manufactured pit bikes, ATVs, and small motorcycles like those from Lifan, Taotao, and Zongshen.
While there isn't a single "universal" manual, most 152FMH engines follow the same service and maintenance procedures due to their standard Honda-clone architecture. Core Engine Specifications Displacement: 107cc – 110cc Type: 4-stroke, single-cylinder, air-cooled
Bore x Stroke: 52.4 mm x 49.5 mm (standard) or 52 mm x 55.8 mm Compression Ratio: 9.0:1 152fmh engine service manual
Transmission: Typically 4-speed manual (1-0-2-3-4) or semi-automatic Power: ~7–8.7 HP at 7,500 RPM Starting: Electric and/or kick start Maintenance & Service Intervals
Regular maintenance is critical for these engines, as they often rely on simple strainer-style oil filters rather than replaceable paper ones. The 152FMH is a widely used 110cc horizontal
Note: Always verify your exact engine code (stamped on the crankcase). The "152FMH" typically means:
- 15 = 52mm bore (approx. 50–70cc)
- F = air-cooled
- M = manual clutch
- H = horizontal cylinder.
Step 2: Top-End Rebuild
- Head Removal: Loosen the four 10mm nuts in a crisscross pattern. The manual warns that the cam chain tensioner (located on the back of the cylinder) must be released before pulling the head, or you risk bending the valves.
- Cylinder Inspection: The manual provides a hone cross-hatch angle (45 degrees) and the allowable taper (0.05mm max).
- Piston Ring Gap: You will learn that the top ring gap should be 0.15mm to 0.25mm. Too tight, and the ring expands until the piston seizes.
Compression Test
- Warm engine to operating temperature.
- Remove spark plug.
- Disable fuel delivery and ignition (pull fuel line or close fuel petcock; ground kill circuit).
- Install compression gauge in plug hole; crank engine 4–6 revolutions on starter/recoil.
- Typical compression: 90–140 psi (6–10 bar) for small 150cc engine; if below spec or wide variance between cylinders (if multicylinder), inspect rings/valves/head gasket.
- Wet compression test: add a teaspoon of oil to cylinder; if compression rises significantly, rings likely worn.
Where to Find a Reliable 152FMH Engine Service Manual
Be cautious: Many online PDFs are for the Honda CG125 or CB125. While similar, there are critical differences in clutch assembly, CDI timing maps, and bolt thread pitches (JIS vs. metric). For the 152FMH specifically: 15 = 52mm bore (approx
- Lifan OEM manuals – Available through Lifan’s dealer portal or aftermarket sellers like ManualsLib.
- Zongshen technical bulletins – Often free as PDFs on ATV community forums.
- General repair manuals – Haynes or Clymer manuals for "Chinese 125cc OHV engines" often include 152FMH data.
- Facebook & Reddit groups – Search “152FMH service manual PDF” in r/ChineseMotorcycles or “Chinariders.”
Pro tip: Look for a manual dated 2015 or newer. Older manuals miss updates like roller rocker arms or upgraded oil pumps.