Husqvarna 2009 TE 310 Workshop Manual page 124

ENGINE OVERHAULING
Check the valve seat, if there are any low spots or other damage, the seat must
be recut. It is important that the contact surface on the valve is in the right place
on the valve. Use marking colour to determine where is the contact surface. The
contact surface should be 0.02 in. from the edge of the valve.
If the contact surface is too low, recut the seat with the 73° and the 45° cutters.
If the contact surface is too high, recut the seat with the 20° and the 45° cutters.
Make sure that the width of the contact surface is correct.
G.4 Part. N. 8000 H0368 (09-2008)