Fork Seals (EZ Install) | Honda CB450 / CB500 / CB550
Standard fork seals on a Honda CB450, CB500, or CB550 can be a fight to install — the traditional seal driver approach requires pulling the fork tubes out of the triple tree and pressing the seal in evenly with a driver sized to the outer diameter. Our EZ Install fork seals skip most of that hassle. They go in without special tools, can be installed with the fork tubes still in the triple tree, and they are made in the USA with a lifetime warranty.
Why You Need This
A leaking fork seal on a CB450 or CB550 puts oil on your disc brake and ruins the front-end feel. Standard-style seals are the OEM-style replacement but they require a proper seal driver and fork disassembly to install cleanly. The EZ Install kit was designed specifically for the driveway mechanic — no bench press, no custom driver, no pulling the fork tubes out of the triple tree. Just pull the old seal, clean, and seat the new one.
These seals are a CMC exclusive, made in the USA, and carry a lifetime warranty. One kit per bike covers both fork legs.
Specifications
| Spec | Detail |
|---|
| Replaces OEM Part Numbers | 91255-KBH-003, 91255-MA6-013, 91255-300-025, 91255-300-033, 91255-292-003, 91255-300-013 |
| Fits Models | CB450 K1–K7, CL450 K1–K6, CB500T, CB500K, CB550K, CB550F, CB750K, CB750F, CB750A, SL350 K2 (see size guide below) |
| Fork Tube Diameter | 35 mm |
| Origin | Made in USA |
| Warranty | Lifetime |
| Sold As | Pair (one kit per bike) |
Important: Pick the Right Size for Your Bike
Honda used two different seal outer diameters on the 35 mm forks across this family. Match the size to your specific bike:
- 35 mm x 46 mm (early size): CB450 K1–K3*, CL450 K1–K4, CB750K0
- 35 mm x 48 mm (late size): CB450 K3*–K7, CL450 K5–K6, CB500T, CB500K, CB550K, CB550F, SL350 K2, and remaining CB750K / CB750F / CB750A
*CB450 K3 mid-production change: Honda changed the fork architecture partway through the CB450 K3 model year. Some K3 bikes use the 35 x 46 mm size and some use the 35 x 48 mm size. The only reliable way to identify yours is to measure the outer diameter of your existing fork seal before ordering. If you are not sure, contact us first.
Model-Specific Notes
- CB450 / CL450 K0 (Black Bomber): Uses a different seal entirely. Not covered by this product. See our CB450 K0 seals for those bikes.
- CB450 K3 mid-production change: Measure your existing seal before ordering. Honda switched seal OD mid-year.
- SL350 K2: Uses the larger 35 mm forks (unlike the SL350 K0/K1 with 33 mm forks). Order the 35 x 48 mm size from this product, not the standard CB350 fork seal.
Installation
Difficulty: Beginner to Intermediate — designed to install without special tools or full fork disassembly.
Installation tip: Lubricate the new seal lip with fork oil before installation. The EZ design lets you seat the seal without a driver, but a light coat of oil on the outer diameter helps it slide into the fork tube cleanly.
Fork Oil Capacities (per leg)
| Model | Capacity |
|---|
| CB450 / CL450 K1–K2 | 290 cc / 9.8 oz |
| CB450 / CL450 K3–K4 | 225 cc / 7.6 oz |
| CB450 K5 / CL450 K5–K6 | 160 cc / 5.4 oz |
| CB450 K6–K7 | 140 cc / 4.7 oz |
| CB500T | 140 cc / 4.7 oz |
| CB500K | 170 cc / 5.75 oz |
| CB550K and CB550F | 190 cc / 6.4 oz |
Honda's factory specification is ATF (Automatic Transmission Fluid), which is approximately 5W. We recommend a motorcycle-specific fork oil in 10W (riders under 200 lbs) or 15W (riders over 200 lbs) for firmer front-end feel.
Fork Rebuild Guides
Honda used several different fork architectures across the CB450 / CB500T / CB500K / CB550 families. Match the right rebuild guide to your bike:
Frequently Asked Questions
What makes these "EZ Install"?
The seal design lets you install it without a traditional seal driver tool, and without pulling the fork tubes out of the triple tree. For most of this family, you can change the seals with the fork still mounted on the bike. The standard-style seal requires a press-in driver sized to the seal outer diameter.
Will these fit my CB450 K3?
Yes, but Honda changed the fork architecture partway through the CB450 K3 production year. You need to measure the outer diameter of your existing seal before ordering — some K3 bikes use the 35 x 46 mm size and some use the 35 x 48 mm size. If you are not sure, contact us first.
Will these fit a CB450 K0 Black Bomber?
No. The CB450 K0 Black Bomber uses a completely different fork and seal. Order the correct seal for the K0 instead.
Made in USA — what does the lifetime warranty cover?
If the seal fails (tears, hardens, weeps prematurely), contact us and we will replace it. The warranty covers the seal itself for the life of the bike.
Do I still need fork oil with these?
Yes. Fork oil goes in after the seal is installed, during fork reassembly. See the fork oil capacity table above for your bike and use a motorcycle-specific fork oil in 10W (under 200 lbs rider) or 15W (200+ lbs rider).
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Last updated: April 2026
