Start of second post…
This is Part 2 of the carburetor dissection. I had second thoughts on how to break up the sections of the carb and decided to do the common paths separately. This means there will be a total of five parts to the dissection instead of four. Now on to the fun…
Fuel Bowl Drain System
When we left off last time the fuel bowl was full, we will now follow the fuel flow to the bowl drain.
Photo 1 – Drain system with components identified:
1 – Float Bowl
8 – Float Bowl Drain Plug
A – Fuel Cross Path (with lead plug removed)
B – Power Adjusting Needle (Gas Adjusting Valve, GAV)
Photo 2 – Fuel exit from the float bowl
18A – Power Adjusting Needle (GAV orifice)
18B – Power Adjusting Needle (fixed orifice)
Photo 3 – Close up of left path.
Note: The GAV can just be seen (bright vertical line) in the orifice.
Photo 4 – Close up of right path.
Note: The small fixed orifice is protected from sediment by the wall surrounding it.
Photo 5 – View of float bowl showing exit path for the fuel
I next removed the GAV (B) and the float bowl drain plug (8).
Photo 6 – Looking into the fuel cross path to the show path of the fixed orifice 18B
This is looking into the fuel cross path from where the lead plug was removed (A on Photo 1). I couldn’t get enough light down the path to show the green wire so I used a light beam to represent the wire. The light beam can be seen as the bright spot in the cross path about 1/3 of the way down. The threads at the bottom are where the drain plug screws in.
Photo 7 – Looking down hole where GAV has been removed to show the path of the GAV orifice 18A (blue wire)
Photo 8 - Looking into the fuel cross path to complete the path, 18A from the float bowl to the fuel cross path.
Photo 9 – Final path through the fuel cross path to the float bowl drain plug (white wire)
Behind the white wire the main jet orifice is visible.
Photo 10 – Side view of lower half of carb showing fuel level and fuel path through GAV
Here I balanced the GAV, with all its parts, on the side of the carburetor. The blue lines represent the fuel paths from the bowl through the GAV to the fuel cross path. The red line represents the fuel level in the float bowl. This shows that the fuel level is a little higher than the top GAV fitting. This is a possible source of leakage if the proper seals aren’t used during assembly of the GAV.
I see no reason at this point to remove the lead plug at the end of the fuel cross path during cleaning, All passages at this point are accessible and can be cleaned with carburetor spray cleaner and compressed air.
The next major post will be the Idle System.
All for now.
Jeff