The repair method for the ablation and wear loss circle of the rear seat hole of the camshaft of the F6L912 engine

The size of the copper sleeve has been determined

1) According to the degree of roundness caused by the wear loss of the cylinder block seat hole, the seat hole is bored by 5-8mm. Round the camshaft journal that is out of round. Measure the radial dimension D1 of the cylinder block seat hole after boring and the radial dimension d1 of the camshaft journal after grinding.

2) Calculation of copper sleeve dimensions

External D = D1+(0.02-0.04mm);

Ensure that the interference fit between the shaft sleeve and the hole seat is 0.02 to 0.04mm.

Within D = d1+(0.07-0.09mm)

Ensure that the clearance between the shaft sleeve and the shaft diameter after press-fitting is 0.03 to 0.07mm.

L= The fit length of the CAM shaft diameter;

d=5 to 7mm(approximately the size of the oil passage in the engine seat).

Selection and processing of copper sleeve materials

1) Material: ZH40(cast brass);

2) The structure of the additional parts is shown in Figure 1.

3 Key Points of Assembly

1) The oil holes of the copper sleeve should be aligned with those of the cylinder block seat holes.

2) During assembly, measures should be taken to prevent leakage caused by poor sealing of the oil plug (see Figure 2).

After the machine was repaired and the valve clearance was adjusted according to the above method, it started successfully at one go and the aforementioned phenomenon disappeared accordingly. During its nearly 1,000 motorcycle hours of operation, this machine has run smoothly and reliably. Not long ago, we used the same method to repair an F6L912 engine with the same malfunction in a certain unit and achieved the same effect.