1. Cam shaft heat treatment hardness is not enough, or the galgoidal rocker R30 arc surface has a chrome-plated hardness exceeds the camshaft hardness (very easy to wear when the oil is missing), so that the camshaft is abnormally worn.

2. The R30 circular arc of the valve rocker arm in contact with the cam lift, and the pulling arm shaft hole is extremely deviation (standard parallelism <0.02 mm), causing the R30 circular arc surface to contact the cam lift partial inclined, severe Only point contact, increase the contact stress, resulting in abnormal wear.

3. The gaseous rocker arc surface chrome-plated layer quality difference chrome layer, adhered to the cam lift portion, plus the cam wear.

4. Camshaft jet oil trough burrs unclear, scratching the inner holes, which in turn pull the camsjh.

5. In the CB125T cam shaft bushing, the outer circle is different, which not only makes the bushing unilateral wear and causes an abnormal wear of the cam journal.

6. The CB125T camshaft journal and the inner hole gap in the bushing are small, and the oil cannot afford the role of floating bearings. The gap is large, too much oil leak, and the lubrication cannot be guaranteed, resulting in abnormal wear.

7. Cylinder head and valve rocker arm seat assembly of the seat hole center deviation, or the contestant arc depth is small, the cylinder head nut is tightened, the rocker seat hole is severely deformed, resulting in a severe of the bearing seat to be severely extruded , The ball deformation is damaged and an abnormal sound is issued.

8. Oilway for camshaft lubrication is blocked by sealing glue during maintenance, resulting in indifferent oil or lubrication and abnormal wear. There are a few engine oil pump filters blocking, and the oil supply is lacking and overheating. The engine generates an overheating, camshaft, and journal, and the bearing bushing can also produce abnormal wear due to other reasons. The friction of the piston, cylinder, etc. also damaged by lack of lubrication.

9. On both ends of the CB125T cam shaft, the spiral groove with left and right rotten spiral grooves is mainly used to guide the oil flow to the cylinder oil tank (lubricating cam lift). The left end has a position keyway of about 4mm and a length of 6 mm. If the left end R1.5 × 1.5 guide oil tank is fixed from the middle space, the lubricating oil is entered into the cam left end from the cylinder head casting oil trail. After guiding the oil tank, most of the lubricants do not enter the cylinder head along the R1.5 × 1.5 guide oil tank, but flow from the positioning keyway of 4 mm x 6mm to the bushing, so that the left end journal of the cam is lacking normal lubrication. An abnormal wear is produced.

10. Horizontal engine oil pump mounting is uneven, making the sealing surface leakage, reduced the pressure of the oil pump, causing the cam bearing lubrication from the farthest oilway, and ultimately leads to the cam and rocker arm wear.