The 3 cylinder 650 and 700 ( 72 to 1980's ) were crossflow ( direct charge ) as Mercury called it.----No reason for a crossflow or loop charge to be hard to start!
That pulse fitting is NOT USED on a regular fuel pump.----The regular fuel pump operates with PRESSURE and not vacuum.-----The regular fuel pump operates off the top crankcase.----The VRO operated off the bottom crankcase.----Remove pulse fitting and put in a pipe plug.
Oil that has been stored in the tank for a long time.-----Possible a wee bit of water mixed in with it due to condensation.----Oil tank should be cleaned / flushed on occasion.
Oil may be thicker in cold , cold weather.----There may be a " gel " at the bottom of the tank.----This would limit oil flow through the filter in the bottom of the oil tank.
Going from 50:1 to 100:1 does not seem like it was based on scientific research.-----If I saw going from 24:1 to 41:1 I would say yes.----Boardroom decisions based on the fact that folks really do not understand what goes on inside a 2 stoke crankcase !!
Agreed the wonderful , smooth running AD-12 model needs the extra oil.-----But once again this thread demonstrates the lack of knowledge of what really goes on once the fuel enters the airstream in the carburetor.----And what really goes on inside the crankcase.
The 2 strokes when maintained use a bit more fuel.----But they do not get sticker shock on repairs / maintenance at $125/hr or more shops.----Locally I see a lot of fairly new 4 strokes for sale.----Must be a reason.