ZHEJIANG KAYO MOTOR CO., LTD.
1. Measure the outer diameter at a height of 7 mm from the piston skirt.
Repair limit value: φ46.96mm;
2. Calculate the cylinder clearance.
Repair limit value:0.1mm
；
3. Measure the inner diameter of the piston pin hole. Repair limit value:φ13.017 mm
4. Check whether the piston has abnormal wear or cracks, and whether the piston ring groove has
abnormal wear.
Repair limit value
：
The first ring
：
0.08mm
The second ring:
0.08 mm
The Oil ring
：
0.08mm
5. Check the carbon deposit on the piston, and clean it in time if there is too much carbon deposit.
6. Put the piston ring into the cylinder, and then measure the closed clearance.
Repair limit value
：
The first ring
：
0.4mm
The second ring:
0.4mm
The Oil ring
：
1.4mm
7. Measure the outer diameter of the piston pin.
Repair limit value
：
φ12.985 mm
8. Calculate the clearance between the piston pin hole and the piston pin.
Repair limit value
：
0.025 mm
INSTALLING THE PISTON RING
The installation steps of the piston ring are as follows:
1. Thoroughly clean the piston ring groove.
2. Install the piston ring.
Note
：
（
1
）
During installation, the piston and piston ring should be prevented from being damaged.
（
2
）
When installing the piston ring, the first and second rings are literally facing the top of the piston, and the
openings are staggered by 180°, and the opening direction is toward the piston skirt; the openings of the two oil
rings must be staggered by 120°
～
180° and cannot be aligned with the piston pin holes. The rings of the piston
should rotate flexibly.
The gap between the rings in the oil ring should match the gap of the spacer ring; when installing the oil ring, the
spacer ring should be installed first, and then the side rails should be installed.
INSTALLING THE PISTON
"IN" towards the intake side of the engine
The installation steps of the piston are as follows:
1. Install the piston, piston pin and new piston retaining ring.
2. Apply proper amount of engine oil to the surface of the piston pin.
3. Then insert the piston into the small end of the connecting rod with the air intake direction upwards, apply a
proper amount of oil to the surface of the piston pin, and then penetrate into the piston pin hole and the small
end hole of the connecting rod.
4. Install another piston pin retaining ring.
Note:
1. When installing the piston, the air intake (IN) direction is upward;
2. There is no deformation after assembly, the retaining ring completely falls into the groove, and the
opening is misaligned by more than 3mm;
3. If the piston pin retaining ring is severely deformed, it must be replaced with a new one;
4. Do not allow the piston pin retaining ring to fall into the crankcase;
5. After the piston pin is assembled in place, there is a slight gap in the axial direction.
INSTALLING THE
CYLINDERBLOCK The installation steps of the cylinder block are as follows:
1. Install cylinder block positioning pins, rectangular rings, and new cylinder block gaskets.
2. Apply a layer of engine oil evenly on the surface of the cylinder block, piston and piston ring.
www.kayomoto.com
