Honda SH125 Manual page 223

Install the drive shaft into the bearing.
Position the assembly collar against the drive shaft
bearing inner race and pull the drive shaft into the
bearing until
it
is fully seated.
TOOLS:
Assembly shaft 07965-VM00200
Assembly collar 07LMF-KAB0110
Apply engine oil t o the lips and outer surface of a
new drive shaft oil seal.
Install the oil seal until
it
is flush with the crankcase
using the same tools.
TOOLS:
Assembly shaft 07965-VM00200
Assembly collar 07 LM F-KA B0110
Apply engine oil t o the gear and shaft sliding sur-
faces.
Mesh the final gear and counter gear, and install the
final gear shaft, countershaft and counter gear into
the left crankcase.
Install the thrust washer onto the countershaft
Install the t w o dowel pins and a new gasket.