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1975 johnson 40 fast/slow speed setting

J

julian

New member
Hi i was wondering buy turning the needle in and making the revs rise is it making leaner or richer.i was going to leave mine at the point just before revs rise to give me a nice idle is this safe for the motor.many thanks julian
 
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(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

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.


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hello mate thanks for the info,so by turning the screw in its making it leaner is that right,so could i just leave at 1 1/2 turns to be safe. thanks julian
 
It is the low speed idle mixture.---------------adjust it for best idle and throttle response ( pick-up )------------------The high speed mixture is fixed ( remove jet to clean it )------------No matter where the low speed setting is , it is " safe " for the motor.
 
It is the low speed setting and you can NOT damage the motor with it even if it is a bit lean !!!!-------If it is too lean the motor will hesitate on acceleration.
 
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