Carburetor question

I have a 1995 125 hp mariner it has 4 carburetors on it. Are the 2 bottom carburetors for low rpms and when I go wide open on the throttle do the top 2 kick in. Or do they work all together at all times. I just can’t seem to understand how this works. I am planning to start to do my own work on it and trying to learn as much as possible. I got the seloc repair manual which I am going thru. I would appreciate is someone could explain this process for me. Thank you very much.

Only the top 2 carburetors provide fuel for the motor to idle.-----So it runs on the top 2 cylinders.-----All 4 sparkplugs have spark all the time.------The bottom 2 cylinders start to run and work once engine runs above 1800 RPM due to air flow through the venturi.-----So get a factory manual .----Read the " fuel / carburetion " section 3 times before doing any adjustments.---At full throttle all 4 carburetors are used.-----Each carburetor feeds the one cylinder directly behind it through the reed valves.-----As I said read the manual 3 times to understand how a 2 stroke engine works !!

THROW AWAY the Seloc manual will be of no use to you for that motor. Take your serial # and get the factory manual. The factory manual has the correct information for the 2+2 motors. That motor is particular about how the link and sync is done and the carburetion in general. Without the factory manual leave it alone.

I really appreciate the info. Where do i get the factory Manuel so I can do more research. I am thinking I will have a someone work on it that know what they are doing.
Till I learn some. Maybe it just seems to be easy to clean carburetors and reinstall and bingo back on the water.