Ok man. Heres a lil tutorial about how to tell and how to adjust them. Death u better count this cause I wanna be a mod soon haha. Ok here goes:
Generally if youre a major motorhead like me and race, I check them every 4 races. Thats 1 time a month maybe once every 2 months. If you have an aftermarket cam, it will be noisy no matter what so just check em. Once you get used to adjusting them you will know what a "loud tick" and a "normal tick" with a cammed up engine is. Stock engine, mine will never sound the same, but just check youre valves as said so by the rest, every 6 months till ya start moddin it up ;D.
How to check and maintain:
You will need:
17mm socket and ratchet set.
10 mm socket.
5mm allen wrech.
feeler guage set that has stock sizes (6-8 thousandths on the exhaust, 4-6 on the intake valve)
BIG flat head screwdriver
4mm wrench
now youre ready.
Take off the crankcase timing mark cap, cam sprocket engine sidecover thing(on head), and valve covers.
Now while you have the socket on the bolt that is holding the cam sprocket on, spin the engine over with that while looking in the timing check hole on the crank. wait till the T (tdc) mark on the mag. lines up with the line on the case. The look up at youre cam sprocket and make sure that lines up with the line on the head. (make sure its a compression stroke).
Now while everythings lined up, take the 10mm and loosen the jamnuts on the tappits on the rocker arms. This will allow you to adjust the tappits up or down.
take youre feeler guage (stock specification clearance) and put it between the tappit and valve stem. then tighten the tappit down with the 4mm wrench and tighten the jamnut. Once done with both intake and exhaust valves, make sure jamnuts are TIGHT, and make sure you can fit the feeler guage you used back under the tappit but noting smaller or bigger.
Then put the valve covers, head side cover, case timing plug, and the tank back on and fire it up.