GPX NC450 - Crankcase and Transmission Repair

Page
37
31
Crankcase, crankshaft, transmission, balance shaft
repair
1. Maintenance instructions 9. Inspection of oil filter parts and oil filter
2. Crankcase decomposition 10. Assembly of transmission/crankshaft/balance
shaft
3. Removal of crankshaft 11. Box closing
4. Inspection of crankshaft 12. Assembly of oil filter
5. Inspection of shift fork/shift fork shaft/shift drum
6. Inspection of left and right box bearings
7. Installation of transmission drum and gear
8. Inspection of main and auxiliary shaft components
Maintenance notice
This section introduces the installation and inspection of the transmission, crankshaft and
balance mechanism. When performing the above work, the crankcase should be separated first,
and the disassembly of other parts of the engine should be carried out before the crankcase is
separated.
Work before crankcase separation
Disassembly of the cylinder head
Cylinder/Piston Removal
Dismantling of clutch, oil pump, shifting mechanism and balance teeth
Disassembly of the magneto
Maintenance parameters of each component
project
Standard value mm
Maintenance limit
mm
shift fork
Inner diameter of countershaft right
shift fork / countershaft left shift fork
inner diameter
φ12.016～φ12.043
φ12.045
Spindle fork inner diameter
φ12.016～φ12.043
φ12.045
Jaw thickness
4.8～4.9
4.8
shift fork
shaft
Outer diameter of main shaft fork
shaft
φ11.973～φ12
φ11.95
Outer diameter of countershaft fork
shaft
φ11.973～φ12
φ11.95
Cylindricity
0.006
----
crankshaft
Inner diameter of connecting rod
small end
φ20.015～φ20.025
φ20.04
Big end side clearance of
connecting rod
Axial
0.15～0.4
0.7
radial
0.008～0.016
0.02
balance shaft
Shaft diameter
φ19.98～φ19.993
φ19.96