Just wanted to add a note here, to help anyone who is confused by a typo in the manual. This has come up before but that info is probably lost in a larger thread. The picture that explains the oil sight glass marks is labeled by an "A" for the upper mark and a "B" for the lower mark -
BUT THEY SCREWED THE POOCH AND REVERSED THE LABELS (see below)
because in the text the "A" refers the reader to the lower mark and the "B" refers the reader to the upper mark...
So, if you were to trust the manual and filled the engine until the level was at the upper mark (labeled "A" in their picture) WHEN COLD you just overfilled the engine! Again, as creeper described above, the difference in oil volume between the upper and lower marks on the sight glass is the area reserved for thermal expansion - when liquids get warmer they expand - and anything above that line will likely escape your engine through a breather vent attached to the airbox. Look for it in there.