The disassembly of valve rocker arm is closely related to the valve mechanism, and the disassembly method is also different due to the different structure of engine and cylinder head. The following is a brief introduction to some of the more typical vehicles.

1. For CG125 and XF125 motorcycles (tappers), it is necessary to ensure that the timing mark "· ·" on the camshaft timing gear must be aligned with the "·" of the crankshaft timing gear, in this state, the piston is in the top center position, and the piston assembly, cylinder cover, tappers and other valve parts are installed respectively. Then install the special valve rocker arm assembly of the tappet model with the SAIC cylinder head, and pay attention to check that the axial clearance of the valve rocker arm on its component shall not be greater than 0.10mm. Excessive axial clearance may cause abnormal sound.

2. For GS125, GN125 and other models, first rotate the crankshaft, run the piston to the top dead center of the compression stroke, remove the CAM chain tensioner and the tachometer driven gear, and then remove the cylinder head cover. Screw out the fixing bolt of the rocker arm shaft, pull out the rocker arm shaft with carp pliers, and then the rocker arm shaft can be removed. Install and remove in reverse order. It should be noted that before installing the rocker arm, the rocker arm shaft must be coated with molybdenum disulfide grease to enhance the lubrication effect.

3. For GY6 and CB125T models, first remove the cylinder cover, then turn the crankshaft to make the piston run to the top stop position (GY6 car should loosen the chain tensioning device), remove the rocker arm seat assembly, screw the M5 thread hole at the top of the rocker arm shaft with M5 bolts, and pull out the rocker arm shaft to take out the rocker arm (GY6 car must also remove the one-way stop plate). When assembling, note that the end of the M5 thread faces outward to facilitate the next disassembly maintenance.

4. For WY125 and JH125 models, first remove the camshaft sprocket, then remove the cylinder head cover, unscrew the rocker arm shaft positioning plate, screw in the rocker arm shaft end with M6 bolts and pull it out, you can take out the rocker arm. Install and remove in reverse order. Before installation, a small amount of oil must be applied to the outer circle of the rocker arm shaft to enhance lubrication.

After the valve rocker arm of these models is replaced and installed, the valve clearance must be adjusted to the specified value of each model. After the adjustment, it should be noted that the crankshaft should be rotated for more than two weeks, and again check whether the inlet and exhaust valve clearance changes. If the change is large, it may be caused by the base circle radial runout value of the camshaft is too large or the shaft journal at both ends of the camshaft and the bearing (sleeve) clearance is too large. It is necessary to find out the cause to avoid abnormal engine sound and other related failures.

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