Yamaha Valve Shim Replacement Tips

Here are some tips on changing valve shims on a 1990 Yamaha Radian. Enjoy!

Step 1 is removing the valve cover (lots of bolts!) and turning the engine to the correct position to measure the clearance of each shim. Remember to take the spark plugs out to make your life easier, and that only certain valves can be measured in each TDC position. The clearance is .11-.15mm for intake and .16-.20mm for exhaust valves. If any valve is out of clearance, you have to remove the existing shim and measure it, then order the appropriate replacement to get the clearance correct. The really useful tip that we learned in this process (that we will share with you here) is that you have to rotate the gap in the valve lifter...otherwise, it is almost impossible to get the shim out.

Here is a picture of the valve we want to remove the shim from. Notice, the gap in the lifter (outer ring) is far to the left, underneath the cam...that means trouble, since we are trying to take the shim out to the right side. The lifter will have to be rotated before the shim can be removed.

Now we have rotated the lifter gap to the right side - ou can see it in the front right. This will make it easy to get our tweezers in to grab that pesky shim. The important thing to know is that you have to do all this BEFORE you insert your shim tool, as once the tool is in, you can't move the lifter. Also, it has to be done with NO CAM PRESSURE on the lifter...the position of the cam lobe in the above pictures is perfect for having a gap between cam and lifter, but still the cam out of the way enough to get a tool on the lifter to rotate it around. So yeah, just put cam like that!

Okay, now our fancy shim tool is in, we have our super fancy tweezers from wallyworld, and that shim is coming right out... Again, notice the position of the cam lobe in all these pictures - in our experience, this was the ideal position for enough clearance for the lifter and the ability to actually reach the shim easily.

Voila! shim is out, ready for the number on it to be deciphered, compared to the chart in the Yamaha manual, and a proper replacement shim ordered. Contrary to reports, we had no problem with removing all the shims, waiting for the new ones to arrive, and then installing those into the shim-less valve lifters. In other words, you don't need to reinstall the old shims and do one at a time. That would be too painful!