Alright, what we're going to do is I'm going to show you guys the difference between top-density compression and overlap. The intake valve is opening, piston is going down. So we're going to fill the cylinder. As the piston comes back up, you'll see the exhaust valve is not moving at all. So now we've got this tight enough combustion area. Our bolt bar valves are closed. Here's a nice close-up showing both valves closed against their seats. But this is where we check valve clearance is when we do maintenance, okay? I should be able to go in here if this has the clearance and I should be able to rotate that bucket with no effort. If I can't rotate the bucket, what do I know? I either have no clearance or possibly on overlap. So should be a clue right away. Makes sense? Okay, so let me keep going here. Now we've sealed the chamber in there. We've powered. Is this combustion as well? So we're going to shove that piston down. Now the piston is still moving down, okay? And the exhaust valve is starting open. What's the intake valve doing? Sealed? It's closed, right? So now we're going to come up and we're just going to fully open the exhaust valve and we're going to shoot those gases out and we're going with them. Watch what we have. We have a thing called overlap. So now of our second time up, okay, piston is all the way up. Look at the canloves. On this particular motor here, they said they're facing each other. Watch. No valve clearance, okay? Doesn't have to be fully open. Just open a little bit. Can you see where there's a gap in there? Here's a nice close up of the valves slightly open in that overlap position just off their seats. Okay, it's just barely off at seat, but both of them on. Watch what happens when I continue on and start the process over again. The exhaust valve was on its way closing if you remember and the intake valve was opening. Okay? So we'll start over. There's intake. Compression. Compression. Compression. Go ahead. Power. Power. Exhaust. Hey, I want to make a video and really spend some time in here because this is an area that every year teaching or training, texture, what not, I see is a problem where people seem to have this lack of understanding of top dead center compression because overlap is not talked about in a service menu because it's not anything needed for us as technicians or maintenance or assembly. So that's why it's not discussed. It's an actual fact that happens, but you're just not going to see it. So people find top dead center and then take for granted that on a four-stroke engine you need 720 degrees or two full revolutions to have a full complete cycle. The big trick here is really if you turn in the motor over in the right direction travel, which when I say right, I don't mean right, I mean correct. You're going to find that when the intake valve fully opens and fully closes and the piston works its way back up the next time around, you will always be on top dead center compression just from intake, compression, power, and exhaust. So if you keep that cool in mind, you should be safe and be good to always set valve clearance, do cam timing and do the needed tasks that we need to do on these engines. I cannot recommend enough if you're unfamiliar, unsure, use the service manual, follow it like a checklist and everything you need is in there. You'll be able to do this well. But hope this video helps. Watch the motor being turned over. There's a bunch of other great stuff on YouTube that shows the cycles and cutaways. This is when we made here at the college. I did with some students took a Ninja motor and that was no good and cut it up and what a useful tool. So hope you enjoyed it and keep on rinsing. If you like what you see here, would you please share it. I'd love you to keep my platform going here on technical education and the ways to be great in your craftsmanship.