Hey there! This bike of mine is my first build of my own. I first started with my friends bike. me being the one with all the tools and know how of mechanical parts. So he is my bike. Its a 29 inch Jeep mountain bike. front disc and rear v breaks. before I put the engine on it I road down the road a few times to see how it rode. Anyway. . . Im trying to get a better understanding of my engine. I had ordered it of ebay, the listing said 80cc but i know that its only a 69cc as far as i can tell from reading around. What I am trying to figure out if my bike is running smooth enough. Its at its probably second tank of gas. and runs great when moving but its still hard to find that sweet spot for idle. I am going to post my youtube video (sorry for the bad video quality but audio sounds good). Can anyone tell me if it sounds like its 4 stroking? and I think I might need to do a better job on the sealing the intake bc it sounds like its idling to long after throttle is down. I have ported both the intake and exhuast to a good size. shortened the intake to fit the carb and just put on the speed carb. She starts up good, im just trying to fine tune it. Being from Illinois its about 39 degrees so it takes a bit longer to warm it up. Let me know what you think! https://www.youtube.com/watch?v=QLnqBYUxGZo Thanks!