Back from vacation and ready to get going again on getting the 1981 Suzuki GS650L back running again. The previous owner had already removed the valve cover, so it made sense to check the valve clearances next so that I can get the top of the engine closed up.
The valve clearance needs to be checked with a cold engine, no problem there when the bike hasn’t run for three years. Specified valve clearance is 0.03mm to 0.08mm and clearances tend to get tighter the longer the engine goes without a valve adjustment. There are a few tools that you will need to check the clearances.
From left to right: 19mm wrench to turn the crank to each valve position, tweezers for removing the valve shims from the tappet, tappet depressor tool to push down the tappet and remove or insert the shim, and a metric feeler gauge.
As noted above the valve clearances are very small numbers and many feeler gauges that you see in auto parts stores don’t have the necessary increments. The one pictured is from Starrett Tools, http://bit.ly/1iNUcFh, and is a bit more expensive than others, but has all of the 0.01mm increments in the specified range and Starrett has a great reputation for measurement tools across many industries. The valve shim tool is from Motion Pro, http://bit.ly/1fIfGD9.
It is important to follow the steps in the manual for checking the clearances or you may got false readings with the springs of adjacent valves affecting each other. It is four positions to check the eight valves. Exhaust 1 and 2 first, then Intake 1 and 2, then Exhaust 3 and 4, and finally Intake 3 and 4. The crankshaft is turned 180 degrees between each valve pair clearance check. The following picture shows Exhaust 1 and 2 ready to be checked with the cam lobe of cylinder 1 pointing forward and the cam lobe of cylinder 2 pointing up.
Another photo with the valve shim tool in place to depress the tappet and remove the shim to determine its thickness. Make sure the valve shim size faces down so that it doesn’t get worn off. This one was a 2.75mm thick shim.
Looks like the valves haven’t been adjusted for a while and are getting pretty tight. The shims shown with x mm are slightly thicker than standard, but I don’t have a micrometer to determine how much thicker. I will be reusing one of the 2.60x mm shims on Intake 2, so that should be slightly less than 0.10mm for the new clearance. Not sure what I am going to do yet on cylinder number 3 since I have not found x shims available for purchase yet. A popular source online for shims is Z1 Enterprises, http://bit.ly/RiF3jv.