1965 40hp johnson help

" I have a 1965 40hp johnson m

" I have a 1965 40hp johnson model#RDS-27M.
The engine starts right up, but I have to keep the choke butterfly 95% closed, or it will start to sputter at an idle. the engine seems to run fine on the water except for full throttle,when it will also
sputter ( sort of like it has the hiccups), I have cleaned the fuel fiter and squirted carb cleaner in the carb. and ran it with fuel additive in the gas to clean out the carb and fuel lines. I also put in new spark plugs.This is my first boat that someone gave me for free. I spent $400 to get the lower unit fixed and new waterpump, plus $200 for a new trailer axel. Now I know why it was for free!!
THANKS IN ADVANCE FOR ANY HELP

Also does any one know the correct way to set the low idle needle valve? do I finger tighten it and put the knob back on in the lean position? "

"Mike.... Spraying anything in

"Mike.... Spraying anything in that carb does absolutely nothing. The cure is to remove, clean, and rebuild it. The proper carb adjustment sequence is as follows.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Joe "