Valve adjustment

I run .0025 intake on all years with no issues. .004 tends to soundy "ticky"
 
I use .003 and .006. Works well. They played with the specs to get the valves as quiet as they could to meet EPA sound levels. Sound levels on a bike are much more than just the exhaust. Air intake, valves, sound that comes straight out of the cylinders and cases. All this is part of the EPA regs. Water cooling is used as much for sound damping as cooling the engine. The water jacket absorbs the noises from the valves and cylinders.
You can tighten up the adjustments a bit more but you may experience a loss of power from the valves leaking and a leaky exhaust valve can burn. I like a bit of noise. This tells me the valves are doing thier job.
Leo
 
I have since gone to .003" on the intakes, If I build a racer motor may go even fatter, there's a well reasoned article on fat valve clearances in the XS650.
 
72-03-20_S288-01_ValveClearanceChange.jpg
 
Yes, it's become the accepted practice to use .003" on the intakes and .006" on the exhausts for all models. Here's a reference chart I drew up comparing the specs from the various years. DO NOT use .002" on the intakes or .004" on the exhausts like some years show. Not sure what Yamaha was thinking when they speced those but they went back to bigger settings on the later years .....

dMOyvrx.jpg
 
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