So about a month ago at 3600 miles ish, I did my own service again. So far all valve checks and adjustments were done by me. All easy! What I notice now is better acceleration, and a couple mph higher top speed.
Valves: like my first check, the upper one was a little bit loose. Instead of barely being able to start the 0.005" gauge, I was actually able to slide it on this time. Not easily, but it was 0.005". I tightened it to 0.004". Anyone know ft the top one is intake or exhaust? Just curious.
Spark plug: this was my first time looking at it. The gap was too tight. I don't remember the spec, but the right gauge would not even go in. The plug had a grey powdery appearance. Basically it looked good other than the gap and the used look. I replaced it with the one I got from parts monster. The new plug was gapped perfect right out of the box. I used the stock recommended plug as I'm a "if it ain't broke, don't fix it" kind of guy.
Air filter: it had a light grey powdery appearance on the salmon covered filter paper. I replaced it with the filter I got from PM.
And of course I replaced the engine oil. I'm using syntec 10W-40 now.
I don't know whether it's one of those things that got me a performance gain, or a combination of all these things. The gain is real though. I've had a few hundred miles to confirm it.