On my GY6 I found running the scoot for a few miles to warm it up, and adjusting the valves hot makes it much easier. I just loosen the lok nuts, and turn the adjuster by hand till it touches the valve stem. That gives Zero play hot, and .003 cold. I've done it one time, and have NOT had to re adjust yet. If you do it carefully you can slide the rocker arm back, and forth but no up or down movement. Just like old school solid lifter cams in hot rods. The engine is perfectly quite, and much peppier. Give it a try!