The engine numbers should be posted but the following is for L-heads; OHV has a different procedure.
On L-heads the valve clearance is checked by removing breather that the cover valve springs (usually on the muffler side of the engine). As far adjusting them it requires removing the cylinder head so the valves can be removed. You will a valve spring compressor so the retaining clips can be removed. To adjust the valve clearance the tip of the valve stem is grounded or file lightly while keeping it squared. After each light filing re-install the valve and check clearance. Be careful not to over file them as you can't lengthen them except by grinding valves or using a new replacement valve.
This is a good time to go ahead and touch up the valve face and seat with valve grinding compound. This will usually close up the clearances again which why I do it at the same time and it just makes good sense to do it while you have the head off and valves loose.
Note: If the valve face are heavily worn then I would replace it anyway and lap with grinding compound for good seat contact.
