This tool is used to hold the bucket down on classic Kawasaki Z1 based engines whilst the shims are changed. Using a spanner or socket on the end of the crankshaft, you turn the crank until the lobe of cam, for the valve you are working on, compresses the spring pushing the bucket down. You then insert the tool so that the little spiggott just holds the edge of the bucket, being secured by the supplied 6mm cap screw inserted in one of the threaded holes used to hold down the cam cover ordinarily. Once the tool is in place, the cam can be backed off by turning the crank the other way. Now the shim can easily be removed. The easiest method is the use a pair of forceps and a slim magnetic pick up tool. Whilst this tool does work the genuine Kawasaki tool is a better bet, but you do pay for the superior tool.