last time I looked behined the drive sprocket the seal (which looked fairly new) it was cantered and in neutral you could hand spin the drive-shaft  with almost no resistance. Once I cleaned all the dirt around the shaft seal with a toothbrush and solvent I reseated the seal with a large sock and hammer tap, I saw no evidence of any kind of crankcase ventilation port anywhere around the drive sprocket. At that point the shaft would still turn but now with slight resistance from the re-seated shaft seal. What I don't understand is if the shaft seal is supposed to allow blow-by of crankcase gases why have a seal in the first place, is the seal intended for dirt only and not oil leaks?  On any account after I had re-seated the shaft seal and installed new sprocket and chain is when I noticed the crankcase pressure during testing, after shutting down to check the oil level the cap popped off while removing the last threads like a cork and a little oil splattered out sort of like a dry pop bottle. After adjusting the carburetor small screw to your recommended 1.5 turns it ran much better but is now sluggish as if the timing advance is not working, but I think its crankcase pressure causing some resistance to the piston bottom end. Unless I can find that crankcase vent to clean out with a piece of lock-wire Ill have to but a used dip-stick and drill my own vent with tubing to carry pressure off. Perhaps Ill find a large bolt in my bolt box and drill my own.
BELOW BEFORE. Seal must have blown sideways from crankcase pressure.

AND BELOW AFTER RE-SEAL. No evidence of case vent anywhere

One thing I hate to admit is that my CT200 is truly slow and sluggish compared to my CT110 like night & day and noise wise the stock exhaust in my CT200 must have burned out baffles becasue it is annoying compared to even my B1250 with Yosh exhaust. Funny I never remember them being that noisy, wish I could rebuild the muffler with glass blanket. 

As a 30 year retired Warrant Gunner God has blessed me with a 1965 CT200 and 1984 CT110, both of which run well and cost me only $1275 for both. For more information about my CT, career, and my life,please visit my personal BLOG/website located on my profile page HERE 8^D.   PLEASE be sure to cut and paste the link into your browser as it has been disabled in my profile, for some reason lol. 8^D...PTL