only time my chain got bound up in there (the drive sprocket recess) was when I stupidly installed that POS "spring loaded" kind of tensioner on my first build,...at startup.
pedal to speed,,..... pop the clutch,...top run of chain goes COMPLETELY floppy-sloppy,,..... floppy chain binds in drive sprocket recess,....almost cracks the crankcase,... rear wheel locks up,... heart attack. (lesson taught,..lesson absorbed.)
it happened at least 10 times before i put on my sherlock hat and found out about that $%#&@((# spring loaded tensioner hunk of JUNK that almost destroyed my engine on the first day. got the standard stock one on there rock solid and it never, ever happened again. coasting, or whatever. clutch pulled, clutch not pulled, uphill, downhill. never again. I will state for the record that im a REAL stickler for chainline alignment, chain tension and lubrication,.. and sprocket mounting concentricity and alignment. ill readjust it all day long until im happy.
that day when my rear wheel locked up in my driveway taught me how disastrous a chain malfunction can really be... not only to the motor and/or wheel,...but ME. but i'll coast with the clutch pulled in a straight line all day long. but,....LEANING while coasting with the clutch pulled? at high speeds? no way. NOPE. leaning makes a slack chain droop and ride off the sprocket. (possibly) and a derailed chain/locked up rear wheel can KILL you. potential death makes me pay attention to detail.