Ok, so i have read the valve adjustment HowTo and it all makes sense apart from the very end where it reads:

   

QuoteSlide a thickness gauge between the camshaft and the shim.
There should be a gap between 0.03mm and 0.08. If it is out of specs, replace the shim with a 0.05mm thinner or thicker.

I have adjusted valves on numerous cars (SOHC) many times but the process on the GS500 seems slightly different. What exactly is replaced if the clearence is beyond tolerance, on a car it is just a case of adjusting the rocker arm tappit.

Any help, i would really like to know a little bit more about what i am doing before i wade in and destroy. 


I am getting "popping" at idle and so i will be checking/replacing:

• spark plugs, leads
• filters (air, oil)
• oil
• valve clearances
• etc...etc...

Thanks in advance,
Richmore

The valve shim is replaced.  Shims come in different thinknesses so the tolerance stays between .03 and .08

I know how dum this is... but what exactly is a valve shim?

The impression i get is that it is some sort of spacer, are they adjustable at all or is it simply a case of "if the clearance is to large/small replace the shim"?

and to think my gf let's me loose on the car...


Thanks,
Richmore

The shim is a coin-shaped block of metal.  It is available in different thicknesses.  If the distance between the cam and the shim is out of spec, replace the shim with a thinner or thicker one as needed.

If you have a speedy connection, download this great how-to video made by Kerry.