I wrote this little spiel for a motorcycle forum I am a member of. I thought some of you chaps might enjoy it too. ;D
I am in the process of bringing my beloved 1994 ZX1100 Ninja back online. Part of the process has been a very thorough strip and clean of the bank of 4 carburettors. The ZX1100 is fitted with a set of downdraft Keihin CVK carbs.
As usual, when I am cleaning a set of carburettors, I marvel at the complexity and beauty of the instruments.
Have you ever taken the time to look closely at a CV type carburettor? All carbs are quite stunning in fact, but the Japanese made ones are simply phenomenal. They must surely be a manufacturing nightmare. The body is the most amazing casting you can imagine. If you hold one in your hands and really study it, you become aware of just how many different facets there are to it. If you have any concept of what it takes to work metal, you begin to see that the die used to cast the body must be a very intricate assembly on its own, featuring many different pieces in order to make the complex shape, and still be able to release the casting from the mould.
That is just one aspect. Turn the casting over and around and look at the many passageways and tiny orifices and jets, and look at how precisely everything must align and fit. There is a veritable labyrinthine maze of internal ducts and tunnels that must allow fuel, air and vacuum to all work in synchronisation - not just in the one instrument, but in a comparable manner across a set of 4 instruments (on a CBX1000 6 instruments!).
Notice that these internal passageways run at a dazzling set of different angles. All these passageways have to be drilled and bored out during the manufacture of the carburettors. So complex are the requirements for these various channels, that they often must be drilled from multiple positions, all of which must line up to make the continuous burrow within the metal - and then the ends of many of the passageways must be sealed shut - and completely airtight. That's what those little steel balls embedded in the outer skin of the body are. You may have noticed them.
Not only is there an intricate array of tiny orifices, but the main bore of the carburettor must also be machined to maintain precise dimensions and fuel/air flow. And still the story does not end there - there is a butterfly valve which has to rotate within that bore, and then seal the bore tightly closed, so the butterfly is not even a simple round plate. It is a very complex oval, with a bevelled edge that when rotated seats just so within the bore of the instrument, closing it off - except for a few microscopic holes that allow just a little fuel / air flow for idle.
The idea of manufacturing such wonderful things in great volume seems ludicrous when one holds one of these up and examines it carefully.
It's easy to say "well it's just made on a CNC machine", and this is indeed true, but there again is an example of superb engineering. The machine in question must be an incredibly precise, 5 axis tool in order to avoid having to constantly reposition the carburettor body for the next operation.
As we all know, EPA requirements, plus the versatility of computer controlled fuel injection have pretty much marked the end for carburettors on vehicles, but coupled with that must surely be the complexity and expense of making such superb devices. Fuel injectors are much less complicated than carbs, mechanically.
So, there you are. I just marvel at carburettors every time I work closely with them. They are fascinating items, and embody so many different things in order to work properly.
Carburettors - a perfect combination of performance, precision and manufacturing know how.
I am in the process of bringing my beloved 1994 ZX1100 Ninja back online. Part of the process has been a very thorough strip and clean of the bank of 4 carburettors. The ZX1100 is fitted with a set of downdraft Keihin CVK carbs.
As usual, when I am cleaning a set of carburettors, I marvel at the complexity and beauty of the instruments.
Have you ever taken the time to look closely at a CV type carburettor? All carbs are quite stunning in fact, but the Japanese made ones are simply phenomenal. They must surely be a manufacturing nightmare. The body is the most amazing casting you can imagine. If you hold one in your hands and really study it, you become aware of just how many different facets there are to it. If you have any concept of what it takes to work metal, you begin to see that the die used to cast the body must be a very intricate assembly on its own, featuring many different pieces in order to make the complex shape, and still be able to release the casting from the mould.
That is just one aspect. Turn the casting over and around and look at the many passageways and tiny orifices and jets, and look at how precisely everything must align and fit. There is a veritable labyrinthine maze of internal ducts and tunnels that must allow fuel, air and vacuum to all work in synchronisation - not just in the one instrument, but in a comparable manner across a set of 4 instruments (on a CBX1000 6 instruments!).
Notice that these internal passageways run at a dazzling set of different angles. All these passageways have to be drilled and bored out during the manufacture of the carburettors. So complex are the requirements for these various channels, that they often must be drilled from multiple positions, all of which must line up to make the continuous burrow within the metal - and then the ends of many of the passageways must be sealed shut - and completely airtight. That's what those little steel balls embedded in the outer skin of the body are. You may have noticed them.
Not only is there an intricate array of tiny orifices, but the main bore of the carburettor must also be machined to maintain precise dimensions and fuel/air flow. And still the story does not end there - there is a butterfly valve which has to rotate within that bore, and then seal the bore tightly closed, so the butterfly is not even a simple round plate. It is a very complex oval, with a bevelled edge that when rotated seats just so within the bore of the instrument, closing it off - except for a few microscopic holes that allow just a little fuel / air flow for idle.
The idea of manufacturing such wonderful things in great volume seems ludicrous when one holds one of these up and examines it carefully.
It's easy to say "well it's just made on a CNC machine", and this is indeed true, but there again is an example of superb engineering. The machine in question must be an incredibly precise, 5 axis tool in order to avoid having to constantly reposition the carburettor body for the next operation.
As we all know, EPA requirements, plus the versatility of computer controlled fuel injection have pretty much marked the end for carburettors on vehicles, but coupled with that must surely be the complexity and expense of making such superb devices. Fuel injectors are much less complicated than carbs, mechanically.
So, there you are. I just marvel at carburettors every time I work closely with them. They are fascinating items, and embody so many different things in order to work properly.
Carburettors - a perfect combination of performance, precision and manufacturing know how.
