10 It's normal for the tappets to spin in the bore. Eventually the top will start to show a circular wear pattern like this. Any sign of wear means the tappets should be replaced. If the cams are replaced, new tappets or buckets should be used as well. The tappets may also show wear on the side where they contact the bore.
11 Some mechanics use an egg carton or a plastic box divided into four compartments, but I use a paper towel to hold the buckets, shims and my notes about clearance. Even though I set the parts down, in order to make it easy to keep track of them I label which bore the tappet came out of.
12 All valve shims are labeled in millimeters. Some manuals have a mathematical process to decide what shim to use, but unless the clearance is way off, one shim size will typically bring the engine back to spec. The problem is that the shims coming out usually aren't legible. You must measure them. This digital caliper was under $20 at Harbor Freight, and it is plenty accurate.
13 The most accurate measurements...
13 The most accurate measurements are those taken with a micrometer. You may have an old one in the family, but it will usually be calibrated in inches. This one was just under $20 from Sears with Craftsman quality and a lifetime warranty. If you must measure in thousandths of an inch, take your micrometer if you have to go buy shims.
14 When you have your shims...
14 When you have your shims selected and installed, make sure the cam bearings are surgically clean and lubed with fresh motor oil or light assembly lube. Install the used tappet buckets in the holes they came from or install new ones. It is a good idea to use a little assembly lube on the cam lobes.
15 Upon reassembly, start...
15 Upon reassembly, start with the intake cam. It will need to set into the head with the timing marks aligned. This Kawasaki has a dot at the top of each cam, and another that lines up with the machined top surface of the head. Next install the exhaust cam. Angle the gear through the chain, then roll it into place. With most engines you will have to hit the timing right, since the chain is usually too tight to jump the chain on the sprocket teeth.
16 This dot on the front of the exhaust cam (marked with white paint pen) needs to be aligned with the upper surface of the head. Some manuals will show a number of pins that should be between the top dots on the cam-chain sprockets. Put tension on the cam chain by pushing your finger through the tensioner hole when checking alignment.
17 Install the cam caps making sure all the dowel pins are in place and that the C-clips are properly locating the cam bearings. Use grease or assembly lube on the threads of the bolts to ensure proper torque values. We wiped these off a bit after dipping them in grease.
18 Torque these bolts very carefully with a quality torque wrench. Make sure the wrench reads down to low enough settings if you have to buy one. The torque spec is so light that these bolts rarely exceed one-quarter turn past finger tight. Work up to the final torque little by little in an X pattern. Now reinstall the tensioner and recheck timing.
All that is left is to double-check the valve clearance, install the valve cover, the seat and tank. The rule of thumb for most mechanics is to shim the valves twice. After the valves have moved (almost always tighter) twice, it is time to replace them to minimize wear on the seats.