LONCIN 125cc Instruction Manual

Loncin 125cc Cylinder head Instruction Manual
Pre-installation inspection
• Check the appearance of the cylinder head for cracks, sand holes and other defects to ensure
that the surface is smooth and flat. At the same time, check whether the valve seat, valve
guide and other parts are seriously worn, and replace them in time if there are problems.
• Confirm that the cylinder head gasket is intact and the thickness meets the specified
requirements to ensure the sealing performance between the cylinder head and the cylinder
block.
Installation procedure
• Install the engine's timing sprocket to the camshaft first and make sure the marks on the
sprocket line up with the marks on the camshaft, then install the camshaft into the cylinder
head and tighten the setting screws, but not too tight.
• Place the cylinder head gasket on the cylinder block, pay attention to the installation
direction and position of the gasket to be correct, usually there is a positioning pin or
positioning hole on the gasket, to correspond with the cylinder block and cylinder head. The
cylinder head is then gently placed on the gasket so that the mounting holes of the cylinder
head line up with the studs on the cylinder block.
• Install the cylinder head fixing screw, tighten the screw gradually in a diagonal way, and
tighten it evenly several times to avoid deformation due to uneven force on the cylinder head.
Generally speaking, the tightening torque of the cylinder head screw should reach the
specified value, such as the tightening torque of the cylinder head screw of the Loncin 125
engine is usually between 2.0-2.4kg.
Adjust the valve clearance
• Turn the engine crankshaft so that the piston is in a compression TDC position, which can
be determined by looking at the mark on the magneto or the mark on the timing sprocket.
• Use a feeler to measure the valve clearance. The clearance between the intake and exhaust
valves is usually between 0.08-0.10mm. If the clearance does not meet the requirements, it is
necessary to adjust the valve clearance adjustment screw until the specified clearance value
is reached.
Lubrication is connected to the cooling system
• Before installing the cylinder head, apply an appropriate amount of oil to the camshaft, valve
rocker arm and other parts to ensure that these parts can be well lubricated when the engine
starts and prevent dry friction from causing damage.
• Connect cooling water pipes or install air cooling devices. For the water-cooled engine,
ensure that the cooling water pipe is firmly connected and there is no leakage; For the air-
cooled engine, it is necessary to check whether the air-cooled channel is smooth and whether
the heat sink is clean and unblocked.
Precautions in use