OldTinBoatGuy
Active member
Hey guys, I would like to run something by you to see if anyone can offer me some insights. I am rather inexperienced at this but I am working on getting an old 1977 Johnson 25hp back in service. It has been sitting for at least 2-3 years maybe longer. Anyway, working on rebuilding the carb last night and all was going well until I started putting it back together.
First off here is a schematic so I can refer to the parts by number, not sure of the proper name of some of them.
The first problem, and to be honest, I am not sure it is a problem, but, referring to the schematic, #17 (Bearing, Needle Valve), was NOT present when I disassembled the low speed needle valve assemble. The manual I am working from along with a couple of schematics of this carb show the bearing being required. The rebuild kit included said bearing but it would not fit easily in the valve seat. It appeared to be too large to go more than about 1/4 of the way into the seat. Anyway, since it wasn't there when I disassembled the carb and the one from the kit didn't fit, I left it out. This decision was reinforced by one additional schematic that did not show the bearing? Go figure. https://www.marineengine.com/parts/...5R77S&manufacturer=Johnson§ion=Carburetor Can anyone confirm that this is indeed how this carb is supposed to be set up? I have too little experience with boat engines and too much conflicting info.
Second question - referring to the schematic, item #19, Main Jet - when I removed what is referred to as the Screw Plug/Drain Plug, it was simply a bolt with a gasket. Beyond it was a void space and when I looked into it, there appeared to be a brass fixture inside, with inside threads. Again the manual was unclear and actually showed an item being removed from the hole? There were scant few instructions and I am wondering if there is a very apparent screw in "jet" that is supposed to be there or if it is there but is relatively deep inside and must be removed with a screw driver or other tool. I cant really see in the seat well enough to tell and I also don't really know what I should be seeing. Any help is appreciated and thanks in advance!
First off here is a schematic so I can refer to the parts by number, not sure of the proper name of some of them.

The first problem, and to be honest, I am not sure it is a problem, but, referring to the schematic, #17 (Bearing, Needle Valve), was NOT present when I disassembled the low speed needle valve assemble. The manual I am working from along with a couple of schematics of this carb show the bearing being required. The rebuild kit included said bearing but it would not fit easily in the valve seat. It appeared to be too large to go more than about 1/4 of the way into the seat. Anyway, since it wasn't there when I disassembled the carb and the one from the kit didn't fit, I left it out. This decision was reinforced by one additional schematic that did not show the bearing? Go figure. https://www.marineengine.com/parts/...5R77S&manufacturer=Johnson§ion=Carburetor Can anyone confirm that this is indeed how this carb is supposed to be set up? I have too little experience with boat engines and too much conflicting info.
Second question - referring to the schematic, item #19, Main Jet - when I removed what is referred to as the Screw Plug/Drain Plug, it was simply a bolt with a gasket. Beyond it was a void space and when I looked into it, there appeared to be a brass fixture inside, with inside threads. Again the manual was unclear and actually showed an item being removed from the hole? There were scant few instructions and I am wondering if there is a very apparent screw in "jet" that is supposed to be there or if it is there but is relatively deep inside and must be removed with a screw driver or other tool. I cant really see in the seat well enough to tell and I also don't really know what I should be seeing. Any help is appreciated and thanks in advance!

