Chopped monoblock question

Does anyone know if the chopped 376/275 carb would have been fitted with this brass bushing where the jet threads in?





I thought that I had some issues running these carbs, and I’ve order a new set (2yrs ago). The new chopped carb does not seem to have this brass fitting, as you can see in the photo. The issue with the new set is that the cylinder running the chopped carb floods like crazy. Wet plugs immediately and won’t start.

New chopped



The older carbs which I replaced seemed to not flood, but did have their own issues with sealing and leaking fuel.

The thing I can’t seem to understand is if this brass bushing is a solution someone came up with for flooding? I also don’t fully understand how the fuel would get into the chamber of the chopped carb with this bushing, as it looks completely sealed off from the fuel banjo/jet block.

Anyone have thoughts or insight into this? I’m a bit puzzled.

seanalex said:

View attachment 124993Does anyone know if the chopped 376/275 carb would have been fitted with this brass bushing where the jet threads in?

View attachment 124994



I thought that I had some issues running these carbs, and I’ve order a new set (2yrs ago). The new chopped carb does not seem to have this brass fitting, as you can see in the photo. The issue with the new set is that the cylinder running the chopped carb floods like crazy. Wet plugs immediately and won’t start.

New chopped

View attachment 124995

The older carbs which I replaced seemed to not flood, but did have their own issues with sealing and leaking fuel.

The thing I can’t seem to understand is if this brass bushing is a solution someone came up with for flooding? I also don’t fully understand how the fuel would get into the chamber of the chopped carb with this bushing, as it looks completely sealed off from the fuel banjo/jet block.

Anyone have thoughts or insight into this? I’m a bit puzzled.

Click to expand...

I presume you are running this with a remote float chamber? If so there is no need for the fuel to enter the float bowl on this carb.

There's a pair for sale on EBay UK, and looking at the pics they also seem to have that bush pressed in, and you can also see the fuel inlets, which should make things clearer.

And here's another pair, where you can clearly see the bush, so it looks a though you need to try and remove it from the old carb, or see if you can get one.

cliffa said:

I presume you are running this with a remote float chamber? If so there is no need for the fuel to enter the float bowl on this carb.

There's a pair for sale on EBay UK, and looking at the pics they also seem to have that bush pressed in, and you can also see the fuel inlets, which should make things clearer.

Click to expand...

so, with this bush pressed in the other larger carb acts as the remote float chamber?

seanalex said:

so, with this bush pressed in the other larger carb acts as the remote float chamber?

Click to expand...

Yes, it certainly seems like it.

Yes, with this set-up, standard on my 1964 650ss, the LH carbs bowl acts for both carbs, hence can't run on a side stand .
My bike wasn't fitted with a side stand.
Runs well otherwise. Obviously there will be fuel flow limitations, but doesn't seem to bother the 650. Apparently also fitted to Atlases.
Cheers

If yours doesn’t have the brass bush, I’m guessing it was designed to run with this float bowl cover on the chopped carb:


The obvious potential downside being that one float chamber wasn’t designed for two carbs, so fuel starvation at WOT is a possibility.

I doubt you’ll be doing prolonged runs at WOT though. But personally I’d be inclined to fit a float bowl extension on the working float bowl, might make you feel better, as it did for many of the ton up boyz !

Ok, this all makes sense now. Much appreciated.