[sc00ter]

Zappa, a soft seize sucks. Not as bad as a lean seize, but still not good. If you pull the exhaust and look up into the cylinder (with the piston at top dead center/ up position) look for smear/scrape marks on the bottom/exhaust side of the piston. That's the start of compression loss.

A straight up lean seize will finish off all compression. Usually scrapes on the bottom/exhaust side of piston and/or a hole in the top of the piston.

Favorite causes of lean/low compression issues:
Leaks around the reed cage assembly.
Wrong settings on the carb.
Wrong heat range on the spark plug, OR plug reach. From buying the wrong plug!
Riding with no muffler or with a serious exhaust leak at the head. Exhaust pulls heat off the cylinder head.
Pod style air filters! No one ever re-jets for them properly.
Other causes, but these are my favorites.