Husqvarna 181 Workshop Manual page 26

8
Crankcase,Crankshaft
Check that the crankshaft rotates easily. If not, readjust it with the fitting
tool.
The crankshaft must be properly centered in the crankcase!
Fit the seal ring on the magneto side. Use fitting tool No. 5025030-08
but on the reverse side.
The distance between the sealing ring and the upper part of the seat (A) should
be 3.5 mm. If lessthe flywheel will damage the sealing ring.
Fit the oil pump (see chapter 2).
Fit the cylinder and pressure test the crankcase (see chapter 2).