Quick valve adjustment question

[supertech411]

I've been studying up on valve adjustment using Bikecliff's pdf. I have a theory question: What is it that wears down that decreases the gap between the shim and the cam lobe? If the shim was wearing down, you would think that the clearance would increase. In the examples, the it was all decreasing clearances which merited replacing the shim with a thiner one.

Thanks!

[blowerbike]

I've been studying up on valve adjustment using Bikecliff's pdf. I have a theory question: What is it that wears down that decreases the gap between the shim and the cam lobe? If the shim was wearing down, you would think that the clearance would increase. In the examples, the it was all decreasing clearances which merited replacing the shim with a thiner one.

Thanks!

the valves wears into the valve seat..
the valve stem moves upwards into the seat making the bucket/retainer rise and become closer to the cam lobe/rocker arm.
hense..you lose clearance.

[supertech411]

Thank you!
So as the wear occurs and the tolerances decrease, friction on the cam increases? What are some of the outward symptoms of the clearances decreasing?

[BassCliff]

Hi,

Tight valves will cause hard starting when cold. If not corrected the exhaust valves will burn.


Thank you for your indulgence,

BassCliff

[blowerbike]

all engines should have some mechanical sounds to them.
tight valves are quiet.
you lose power because the valves become pushed off of the seat and begin to leak compression.
loss of power.
i believe that you can have popping throught the exhaust and or the intake sides where things are starting to mix up.
exhaust valves will burn if this happens and is not corrected within a reasonable amout of time.
if you have any question as to when the last valve adjustment your motorcycle has had.................................
remove the valve cover and check them..
ok typing sucks i must stop now.

[Nessism]

Top photo shows valves that were not adjusted and burned, other photos shows good valves.