Carburetor O-Ring Kit | Honda CB350 / CL350 / SL350 K0
Complete carburetor o-ring replacement kit for Honda 350-series twins with Keihin CV carburetors. One kit includes enough o-rings to seal both carburetors — covers all early and late carburetor generations.
Why You Need This
As rubber ages, it shrinks and hardens — especially in carburetors where o-rings are constantly exposed to gasoline, heat cycles, and evaporation. Dried-out o-rings are the most common cause of fuel leaks from the float bowl, mixture screw, and jet passages on these vintage Hondas. If your carbs are seeping fuel or you're doing a rebuild, replacing every o-ring at once is the smart move.
The o-rings in this kit are specifically sized to replace the original Honda o-rings and are a direct fit. No trimming or modifications needed.
Specifications
| Spec | Detail |
|---|
| OEM Part Numbers | 16010-344-305, 16010-344-690 |
| Fits Models | CB350 K0-K5 (1968-1973), CL350 K0-K5 (1968-1973), SL350 K0 (1969-1971) |
| Sold As | One kit — rebuilds both carburetors |
| Carburetor Type | Keihin CV (Constant Velocity) |
Note: The o-rings in this kit were designed to fit the various types of Keihin CV carburetors fitted to the 350-series twins throughout their production life. Not every o-ring included in this kit will fit your specific generation of carburetor — use the ones that match your float bowl style and jet configuration.
What's in the Kit
- Large, early-style float bowl o-rings (2)
- Small, mid/late-style float bowl o-rings (2)
- Needle seat o-rings (2)
- Late-style float bowl drain plug o-rings (2)
- Main jet o-rings (2)
- Secondary jet o-rings (2)
- Late-style mixture screw o-rings (2)
Installation
Difficulty: Intermediate
- Remove the carburetors from the bike and disassemble the float bowl, jets, and mixture screw.
- Remove all old o-rings from the float bowl groove, jet seats, needle seat, drain plug, and mixture screw.
- Clean the o-ring grooves thoroughly — old rubber residue prevents a good seal.
- Lubricate each new o-ring with a thin layer of oil before installation.
- For the float bowl o-ring, give it a gentle stretch before seating it in the groove. Use a dab of white grease or petroleum jelly to hold it in place while you reassemble.
- Reassemble the carburetors and check for leaks before reinstalling on the bike.
Our CB350 carburetor rebuild video series covers full disassembly, jet installation, float height setting, and sealing the float bowl with new o-rings.
Frequently Asked Questions
Will the round o-ring work on the square/house-shaped float bowl?
Yes. The standard round o-ring float bowl seals work in the house-shaped grooves of the CB/CL350 float bowls. They seat and seal properly despite the different groove shape.
What's the difference between this kit and the full carb rebuild kit?
This o-ring kit includes only the rubber seals — the o-rings for the float bowl, jets, needle seat, drain plug, and mixture screw. Our Carburetor Rebuild Kit includes the o-rings plus jets, float needle and seat, gaskets, and other wear items for a complete rebuild. If your carbs just need sealing, the o-ring kit is all you need. If you're doing a full rebuild, get the rebuild kit instead — it includes all the o-rings.
How do I know which o-rings to use for my specific carbs?
Honda changed the CB350 carburetor design across production years. The kit includes o-rings for early, mid, and late carburetor generations. Match the o-rings to your float bowl shape — early carbs use the larger float bowl o-ring, mid/late carbs use the smaller one. Use the o-rings that physically fit your carburetor and set aside the rest as spares.
Does this fit the CB360?
No. The CB360 uses different Keihin carburetors with different o-ring sizes. See our CB360 Carburetor Rebuild Kit for the correct parts.
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Last updated: April 2026
