Husqvarna TE 250 - 310 2011 I.E. Workshop Manual page 136

ENGINE OVERHAUL
Install the new guide from the top of the head using a suitable punch. Smear the
guide with oil before installation.
Ream the valve guide using a suitable reamer and lubricate with cutting fluid.
Rotate the reamer when extracting it to avoid scoring the valve guide.
When a valve guide is changed, the valve seat must be refaced.
Check clearance again as outlined above.
Refit the sealing rings (1).
G.6 Ed. 07-2010