NC250发动机维修手册(正式版)-英文0520

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汽缸头盖的拆卸 Removal of cylinder head cover
1.拆下汽缸头盖进气、排气两侧气门室盖的 4 颗 GB/T16674 小盘 M6×20 的紧固螺栓；
2.拆下气缸头进气、排气两侧的气门室盖； 1. Remove the 4 GB/T16674 pan head M6×20tightening bolts from both valve the valve covers on both intake side and exhaust side on the cylinder head ; 2. Remove valve covers on both intake side and exhaust side from the cylinder head;
Primary ratio
1stBaidu Nhomakorabeagear
2nd gear
Gearing
3rd gear 4th gear
5th gear
6th gear
Manual wet multi-plate Normally engaged two-stage
6-speed transmission Reciprocating manoeuvre with left
气门座工作面宽度 Valve seat work face width
进气 Intake 排气 Exhaust 进气 Intake 排气 Exhaust 进气 Intake 排气 Exhaust
各部件维修参数 Maintenance specifications for all components
维修须知
Maintenance instructions
注意事项： Cautions:
● 凸轮轴润滑由缸头上油道经摇臂轴油孔而润滑的，缸头上的油道绝对不能有异物 进入，并保持畅通。
● Keep foreign matters from going into oil gallery through the cylinder head and oil gallery unobstructed in case camshaft is lubricated by allowing oil to go into oil gallery through the cylinder head and via oil port on rocker arm shaft.
气门间隙 Valve clearance
凸轮轴基圆跳动 Camshaft basic circle runout
0.05～0.3
0.016～0.045 48.35
0.04～0.06 0.02
维修极限值 mm Maintenance limit value
mm 0.5
0.08
47.5
------
0.04
3、 缸体、活塞、活塞环 ----------活塞环间隙过大或断裂 ----------活塞有裂纹或过度磨损 ----------缸体内径过大或砂眼 3. Cylinder block, piston, piston ring ----------Excessive piston ring clearance or broken piston ring ----------Cracked or overly worn piston ----------Excessive cylinder block bore or blistered cylinder block bore
Main technical specifications
Engine
Transmission system
Ignition system
Fuel
Items Model
Type, number of cylinder Bore×Stroke
Cylinder displacement Compression ratio Type of carburetor Air cleaner Lubrication system Starting system
噪音过大或异响 1、 气门调整不正确 2、 气门卡住或气门弹簧断裂 3、 上摇臂过度磨损 4、 配气正时不准 5、 凸轮轴磨损 Excessive noise or S&R 1. Improper adjustment of valve 2. Stuck valve or broken valve spring 3. Overly worn upper rocker arm 4. Improper valve timing 5. Worn camshaft
项目 Item
气门 Valve
气门杆外径 Valve stem outer diameter
气门导管内径 Valve stem inner diameter
气门杆与导管间隙 Valve stem -to- guide clearance
汽缸头 Cylinder head
气门密封带宽度 Valve sealing strip width 平面度 Surface flatness
标准值 mm Normal value mm
φ4.972～φ4.987
维修极限值 mm Maintenance limit value mm
φ4.96
φ4.96～φ4.975
φ4.94
φ5～φ5.012
φ5.035
φ5～φ5.012
φ5.035
0.013～0.04
0.07
0.25～0.052
0.08
clearance ---------- Poor valve tightness ---------- Improper valve timing ---------- Broken valve spring
2、 汽缸头 Cylinder head ----------火花塞与汽缸头连接不紧密 ----------汽缸头垫损坏 ----------汽缸头有裂纹或砂眼 2. Cylinder head ----------Poor connection between spark plug and cylinder head ---------- Damaged cylinder head ----------Cracked or blistered cylinder head
3.拆下紧固缸头盖的 2 颗 GB/T16674 小盘螺栓 M6×60、2 颗 GB/T16674 小盘螺栓 M6×35、4 颗 GB/T16674 小盘螺栓 M6×30，取下 2 颗 A88 进气 管垫圈并将其装到 M6×60 的螺栓上； 3.Remove 2 GB/T16674 pan head bolts M6×60, 2 GB/T16674 pan head bolts M6×35, 4 GB/T16674 pan head bolts M6×30 and 2 A88 intake gaskets from the cylinder head cover and install such 2 A88 intake gaskets on the bolts M6×60;
foot 2.91
2.58
1.8
1.33
1.1
0.96
0.88
Mode of ignition Spark plug
Spark plug gap
C.D.I (contactless ignition)
Equivalent to Champion RG6YC and spark plug with flat seating in function
0.7mm-0.8mm
Grade of fuel
≥RQ93
Specification
SJ 5W/40
Oil
Capacity
C
1.5L
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汽缸头和气门
Cylinder head and valve
维修须知 Maintenance instructions 故障排除 Troubleshooting 汽缸头盖的拆卸 Removal of cylinder head cover 摇臂检查 Inspection of rocker arm 汽缸头的拆卸 Removal of cylinder head 汽缸头的分解 Disassembly of cylinder head 气门和气门弹簧的检查 Inspection of valve and vale spring 气门座的检查、研磨 Inspection and grinding of valve seat
Max. power/Corresponding RPM Max. torque/ Corresponding RPM
Specifications ZS177MM
Single cylinder, water cooling, 4 stroke, SOHC
φ77×53.6mm 249.6ml
（11.1～12）：1 Vacuum diaphragm type
汽缸头的检查 Inspection of cylinder head 测量气门座接触面的宽度 Measuring width of mating face at valve seat 汽缸头的组装 Assembly of cylinder head 汽缸头盖的组装 Assembly of cylinder head cover 凸轮轴的组装 Assembly of camshaft 汽缸头的安装 Installation of cylinder head 汽缸头盖的安装 Installation of cylinder head cover
1.5
----
0.04
0.05
0.8
----
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故障排除 Troubleshooting
缸内气压低： Lower pressure inside the cylinder 1、 气门 ----------气门间隙调整不正确 ----------气门密封不严 ----------配气正时不对 ----------气门弹簧断裂 1. Valve ----------Improper adjustment of valve
● 在安装汽缸头之前，缸头定位销一定要装配好。 ● Cylinder head locating stud shall be installed in place before installing cylinder
head. ● 凸轮轴不能有划伤痕迹，装配时先打上机油。 ● Camshaft shall be free of any scratch and apply oil onto it before installation
排气有黑烟 1、 气门导管磨损 2、 挡油罩渗漏或损坏 3、 汽缸头垫渗漏 4、 活塞环间隙过大
Black smoke mixed with exhaust gas 1. Worn valve guide 2. Oil-proofing cover with leakage or damaged oil-proofing cover 3. Cylinder head gasket with leakage 4. Excessive piston ring clearance
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项目 Item
标准值 mm Normal value mm
摇臂与缸头盖摇臂开档的轴向间隙 Axial clearance between rocker arm and cylinder head rocker arm opening
摇臂与摇臂轴的径向间隙 Rocker arm –to- rocker arm shaft radial clearance 气门弹簧自由长度 Free length of valve spring
Dry sponge Pressure + Splash Electric start + kick start 18.5(1±5%)kW/9000(1±5%)rpm 22(1±5%)N.m/7000(1±5%)rpm
Idling
1500±100 r /min
Clutch Transmission
Shifting system