Engine Trouble Whats this noise? (Video) 66CC 2 Stroke


New Member
Nov 7, 2019
Hi!, I have a newer build currently at 104 miles, running 30:1 full synthetic. Its a CDH 66CC with high compression head, copper head gasket, upgraded C Clip CW10, and upgraded open port jug running a NGK B7HS. I have one gasket on bottom of jug. This thing rips all the way to 37 MPH with a ton of low end torque, there is no need to red line it.... BUT. for the last couple days when starting cold, i heard this sound like air escaping from some where but would go away after a few secs, and would always start, until i was really ripping on it when warm, it started making this sound again, but this time it stalled out, and gave the feeling of low compression. I thought the rings or piston were shot, took all apart, and everything is like new tight, clean, with no abnormal wear. The only thing that seemed questionable, was the one or two of the head bolts are slightly stripped because of the acorn nuts. But i was able to tighten them down enough, and the sound went away. Does this sound like a lose head because the bolts are not holding enough tension?

As of right now, they are semi tight, and it runs perfect, and i did not see any damage to engine, piston, rings, or jug...

Am i over thinking this? I am going to upgrade nuts today.




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