Valve Springs should be part of your routine maintenance routine. You will see recommendations that suggest replacement anywhere form every 2 races to every 6 races. I like the middle....every 4 races. Place the piston at TDC to prevent the valve from falling into the cylinder, although the stem seal should hold the valve up. Pressurizing the cylinder to hold the valve up is optional. Several pair of needle nose pliers, extra hands and patience will be required! Briggs offers a valve spring tool part# 19347. They are available from a Briggs dealer or online at www.briggsandstratton.com. Valve lash settings are also a point of great controversy. The Briggs manual recommends .004” Int./.006” exh. A Bando engine builder, (back when there was such a thing) , recommended .010” int. 012” exh. I like .006”int/.008”exh

Heady Duty valve spring part #809374 is now available from 600 and Briggs. When installing this spring remove one of the two shims under the spring.