I had my valves extremely tight on my bike due to the previous owner not oiling his air filter, so the seats wore down, leaving me with anywhere from no to 3 thousands at the most gap on my intake. All I did was put them back in spec and change my sparkplugs from some autolite crap a Harley dealer put in to some NGKs and the power is very noticeably more, I actually accidentally did a mini burn out when I hit the power band in first gear. So long story short, check those valves on schedule, your bike will pay you back in horsepower and engine life.

 

Same as with any vehicle. Regular maintenance is KEY.

 

Having to change valve shims for periodic adjustment has nothing to do with oiling an air filter. For example: If you had to add that much oil to the air filter of a fuel injected car or bike so it was dripping into the intake valves, or even misting them, you would not have a singe operational sensor on the induction side. The MAF or even MAP would be full of oil and the vehicle would not run, or run poorly. Oiling the high flow aftermarket filters is to collect dirt particles.

Adjusting the valves is necessary periodically because the valves slap shut an unsaid amount of times during the life of an engine and you have several metals that expand, contract, wear, and flatten all at different rates, and this causes us to have to adjust the valves. The clearances on these machines tend to diminish over time. All normal. Glad you put the right plugs in and I personally think it is awesome that you adjusted your own valves.