Honda CB600S 2001 carb rebuild

Question

I recently bought a 2001 Honda CB600S, with 35000km on it. Unfortunately fuel consumption has been terrible, and I drive roughly 1 liter per 12km. When taking it to a specialist in carburateurs, he noticed the hole which the jet needle (long pointy needle which can move, part 16012-MBZ-610) is supposed to block/regulate was worn out. Apparently in Hondas those holes are not replaceable, while in other brands there's a separate part there which you can just screw out and replace.

Now this did get me confused. From what I understand, the jet needle slides in and out of the needle jet (discontinued but available at chinese quality and price, part 16156-MBZ-610). But looking at the " Carburetor (component parts)" diagram, and looking at youtube videos, the neele jet and jet needle seem to be at a roughly 45 degrees angle of one another.

My questions:

1. Does the jet needle slide into the needle jet? If not, what is the name of the hole it does slide into?
2. Can the needle jet be screwed out and replaced with a chinese quality one, or is it indeed "crimped"/slammed into place?
3. Does the kit linked down below (image attached) indeed include the needle jet?

I know I should not expect aftermarket products in a carb to deliver peak performance or efficiency, but would hope better efficiency than worn-to-the-bone OEM parts.

https://www.bike-parts-honda.com/honda-motorcycle/600-MOTO/HORNET/2001/CB600F21/Engine/CARBURETOR-COMPONENT-PARTS-/13MBZW41/E__1801/1/1461

Repair kit I'm looking at: 4 Sets For HONDA CB600F Hornet PC34 1998-1999 CB 600F CB600 F PC 34 Float Needle Seat Parts Carburetor Rebuild Repair Kits https://aliexpress.com/item/1005005518495478.html

Answer 1

1. Does the jet needle slide into the needle jet? If not, what is the name of the hole it does slide into?

No it does not. The jet needle slides into some other brass piece sitting at the bottom of the carburator opening and reaching into the float chamber. This part is not “holder, needle jet” (part #24).

The part your are looking for is not pictured in Honda's parts catalog. I don't think it is intended to be replaced.

Keihin VP4AA carburator viewed from engine side with the jet needle fully slided into its counterpart:

Keihin VP4AA Carburator view from bottom with float chamber cover taken off and jets removed:

The jet needle slides into the slimmer and longer of the 2 brass pieces protruding into the float chamber.

The “holder, needle jet” (part #24) screws into one of the 2 holes. As you can see, it is indeed angled about 45°.

Regarding questions 2 and 3: Yes and yes. But the needle jet holder is not the part you are looking for.

BTW: From the pictures I would say that the kit does not include the gaskets you will need for carburator combination. You will also have to buy 2 x “gasket set B” and 2 x “gasket set C”.

Source: I have recently overhauled a set of Keihin VP4AA carburators of a 2005 Honda CBF600SA.

Answer 2

The jet needle does indeed slide up and down within the needle jet as throttle is opened and closed. The jet needle (part 3) is fixed to the throttle slide (part 20). I suspect the 45 degree angle (part 24) on the picture is for illustration purposes only and this is not the case on the real parts.