How to rebuild the factory Keihin CV carburetors on your Honda CB350 / CL350 / SL350 K0

Key Technical Steps:

• 01:32 - Remove the diaphragm cover first to create a flat workspace.
• 06:30 - Jet Retainer: The retainer clip has a specific slot width; it only fits one way.
• 13:00 - Emulsifier Tubes: Use a wooden chopstick to press these out from the top to avoid damaging the brass.
• 17:50 - WARNING: The mixture screw washer and O-ring often get stuck inside the body. Fish them out with a pick.

Full Transcript:

Full Transcript: Disassembly Procedure

[00:00] Introduction & Identification
This is a "Late Style" carburetor, easily identified by the large drain plug and the internal idle mixture screw. Note that on the CB350, the left and right carburetors are mirror images of each other, so the same disassembly process applies to both.

[01:32] Diaphragm & Slide Removal
The first step is to remove the top cover. Caution: Keep your thumb on the cover as you loosen the screws because there is a large spring underneath that will pop out. Remove the spring and the diaphragm slide. Inspect the rubber diaphragm by stretching it gently under a bright light to look for tears or pinholes. If damaged, you will need a replacement (Part #6034).

[05:13] Float Bowl & Jets
Remove the four screws holding the float bowl. Inside, you will find the main jet retainer, which holds the primary and secondary main jets in place. This retainer has a specific slot width that matches the overflow tube, so it only fits one way. Remove the retainer (Part #6045), the jets, and the float. A quick way to check your float is to shake it near your ear—if you hear liquid inside, it is leaking and must be replaced (Part #6068).

[10:22] The "Secret" Rubber Plug
There is a small black rubber plug located near the jets that is often overlooked. It looks like a mini cork. You must remove this for cleaning. If it is missing, your rebuild kit will include a replacement.

[13:00] Removing Emulsifier Tubes (The "Chopstick" Method)
The emulsifier tubes (discharge nozzles) are pressed into the carburetor body and can be difficult to remove. Do not use a screwdriver to pry them out, or you will break the brass tabs. Instead, support the carburetor body on two blocks of wood. Use a soft tool, like a wooden chopstick or plastic punch, to press the nozzles down from the top (slide side) until they pop out the bottom.

[16:48] Mixture Screw Extraction
Finally, remove the idle mixture screw. Be very careful here: the spring usually comes out with the screw, but the tiny metal washer and the rubber O-ring often stay stuck inside the hole. You must fish them out with a dental pick. The correct order for reassembly is: Spring → Washer → O-Ring.

Key Technical Steps:

• Installation Order: Emulsifier tubes first, then jets.
• Float Needle Seat: Ensure the aluminum washer is installed under the brass seat.
• Orientation: Align the main jet retainer with the overflow tube slot.

Full Transcript:

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Key Technical Steps:

• Measuring: Hold the carb at an angle so the float tang just touches the needle without compressing the spring.
• Spec: 23mm to 26mm depending on the model.
• Sealing: Ensure the new float bowl O-ring is seated in the groove before tightening.

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Key Technical Steps:

• Inspection: Hold the rubber diaphragm up to a light source to check for pinholes.
• Alignment: Ensure the slide tab aligns with the groove in the carburetor body.
• Spring: Place the spring carefully under the cap to avoid binding.

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Key Technical Steps:

• Mixture Screw Order: Spring → Washer → O-Ring.
• Initial Setting: Lightly seat the screw, then back it out 1-1/8 turns (verify per manual).
• The "Clunk" Test: Lift the slide with your finger and let go. It should fall smoothly and make a distinct "clunk" sound, indicating a good vacuum seal.

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