What is the function of the orifice plug

[Webekin]

My 3 hp Johnson JWF -22 carb has the orifice plug and stud where other 3 hp carbs have a high speed adjustment. Is there a standard setting for this orifice plug? Webekin

 

[racerone]

That is not adjustable !!-----It has a calibrated hole to allow the correct amount of fuel through.----That is if the motor is pulling the correct amount of air through the carburetor.-----Install it snug.

 

[Webekin]

Thank you! I read the carb cleaning link also good info there. Webekin

 

[Webekin]

So back to the JWF 22, the carb. Kit has been installed, and it will start, if the throttle is almost full, but it runs as if it is to rich. So reduced the fuel flow at the shutoff valve, to the point of shutting off fuel. At this point it began to increase in RPM's, ran great until it ran out of fuel! What will cause it to run rich? Considering changing the needle again, if it is leaking fuel when the float is up and the needle should be seated closed.

 

[kbait]

Check for float valve seating (blow into inlet with carb inverted..no air should pass). Missing nozzle gasket will also cause your issue. #36

 

[F_R]

So back to the JWF 22, the carb. Kit has been installed, and it will start, if the throttle is almost full, but it runs as if it is to rich. So reduced the fuel flow at the shutoff valve, to the point of shutting off fuel. At this point it began to increase in RPM's, ran great until it ran out of fuel! What will cause it to run rich? Considering changing the needle again, if it is leaking fuel when the float is up and the needle should be seated closed.

You ask what will make it run rich.

1. wrong orifce plug
2. somebody drilled out the orifice plug or jammed wires, or whatever through it. That is a precision hole.
3. thick gasket missing from center of carb bowl. (comes with a kit).

 

[saltchuckmatt]

So back to the JWF 22, the carb. Kit has been installed, and it will start, if the throttle is almost full, but it runs as if it is to rich. So reduced the fuel flow at the shutoff valve, to the point of shutting off fuel. At this point it began to increase in RPM's, ran great until it ran out of fuel! What will cause it to run rich? Considering changing the needle again, if it is leaking fuel when the float is up and the needle should be seated closed.

All kinds of things but let's back up. When you run it full it's on a boat right? And not in a bucket.

Turning off or starving it of fuel leans it out so yes they may lead you to believe it's running rich but it's also starving the motor of lubrication and could be doing harm to it. You should stop doing that.

 

[Crosbyman]

does it smoke excessively...? have you checked compression ? what are numbers ?

"Kit has been installed, and it will start, if the throttle is almost full"

why ? the low speed circuit of the carb should allow easy starting...have you fully cleaned the carb incl. the top idle drip chamber under #7 and the very small channel on the side of the top carb half portion. ??

 

[Webekin]

Check for float valve seating (blow into inlet with carb inverted..no air should pass). Missing nozzle gasket will also cause your issue. #36
View attachment 375815

Sure enough, my helper installed the nozzle gasket yesterday, and we put it into a tub of water today, and it started on the 3rd pull. Ran nice, idled down, and died then restarted on 2 pulls. accelerates nicely, and then idles back well. thanks for the tip on the nozzle gasket. I was sure it was something simple. Webekin.

 

[kbait]

Thanks for posting your resolution. Enjoy!

 

[oldboat1]

glad you got it fixed. #39 is the critical piece for high speed operation -- needs to be cleaned now and then, as it has to be squeaky clean. Carb cleaner works well with the plastic nozzle attached. I don't like to remove them because they are easily damaged. A piece of weed wacker line, carefully used, works if it is really jammed up.