Main Jet change questions BS-38

[garyr]

I remember 5 twins mentioned you can remove the bowel drain screws and change the mains without taking the carbs off. I have 78 carbs and was wondering If I remembered it correctly.

 

[5twins]

Well, yes you can if you didn't install them using a big old screwdriver and Magilla Gorilla force. With the carbs installed, you're only going to be able to use a stubby screwdriver. If you installed them super tight using a full size screwdriver, that stubby ain't gettin' 'em out.

 

[garyr]

I'm not explaining myself well. The large 10 or 8mm (socket ) fuel drain bolt...if you remove that is the jet-main accessible through that hole. Thanksks 5 twins..

 

[5twins]

Yes, it's in that hole, actually mounted in the float bowl bottom - from the bottom. It's not screwed into the main carb body like the BS34s and most other carbs. If you can't get it loose through the drain bolt hole, bowls still mounted, you can just remove the whole bowl and try. The jet will be coming off with the bowl. It's easier just dropping the bowls than pulling the carb set.

 

[5twins]

My tool of choice for most of the carb screws and all the jets is this little Craftsman knurled bit holder. It allows you to make things tight enough but not too tight .....

For getting out the really tough ones, it has a 1/4" drive hole on the bottom so you can snap a ratchet on it .....

 

[garyr]

5 twins...I remember about 7 years ago or so you helped me with jetting problem and you said you can change the main jet on the side of the road.. Now it all comes back to me, when you unscrew the drain plug the main jets was right there..had to take apart nothing else. The small Tupperware bowel catches the fuel perfectly.

I recently had some engine performance work done and the engine breathes better but I needed to richen the main jet because my pipes were starting to yellow and developed a slight hesitation around 5.5 rpms at hard acceleration.