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1978 Honda CB750K Master Cylinders & Reservoir Parts

Before replacing or rebuilding the master cylinder on your 1978 Honda CB750K, identify the unit and brake-light arrangement already fitted. The route includes internal rebuild parts, reservoir pieces and replacement assemblies. Some replacement listings explicitly require a separate brake-light switch for this year.

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Currently viewing Master Cylinder & Rebuild Parts

Honda motorcycle parts

Choose your model and year to see parts listed for your bike.

Honda CB750 CB550 CB500 master cylinder rubber boot 45522-300-010

Honda CB Master Cylinder Rubber Boot ~ Replaces 45522-300-010

$9.95 USD
33-0003
Replace your master cylinder rubber boot with this Master Cylinder Rubber Boot, which attaches where the brake hose joins the master cylinder. Replaces OEM...
New
Honda CB750 CB550 CB400F front master cylinder assembly 5 8 in.

Honda CB Front Master Cylinder Assembly ~ 5/8 in.

$99.95 USD
08-0253
Drop in a factory-look master cylinder with a performance piston size using this Front Brake Master Cylinder Assembly. Black body with silver lever, custom-manufactured...
Sold out
Honda CB900 CB750 CB650 front master cylinder assembly

Honda CB900 / CB750 / CB650 Front Master Cylinder Assembly

$109.95 USD
08-0457
Fit a blacked-out front master cylinder to your late-'70s or early-'80s DOHC CB with this Front Brake Master Cylinder Assembly. Usable on any single...
Honda CB750 CB550 CB400F master cylinder diaphragm 45520-300-000

Honda CB Master Cylinder Reservoir Diaphragm ~ Replaces 45520-300-000

$10.95 USD
08-0282
Replace a hardened or torn master cylinder diaphragm with this Master Cylinder Reservoir Diaphragm, replacing OEM #45520-300-000. Exceptional range of applications, fits FRONT master...
Honda CB750 CB550 CB400 front master cylinder kit 45530-404-315

Honda CB Front Master Cylinder Rebuild Kit ~ Replaces 45530-404-315

$59.95 USD
08-0281
Service your late-'70s CB750K/A, CB550, or CB400 front master cylinder with this Front Brake Master Cylinder Rebuild Kit, replacing OEM #45530-404-315. Made in Japan.Key...
New
Honda CB750 CB550 CB400F front master cylinder assembly 14mm

Honda CB Front Master Cylinder Assembly ~ 14mm

$99.95 USD
08-0269
Restore strong and consistent braking performance with this Front Brake Master Cylinder Assembly, designed as a high-quality replacement for many classic Honda models. This...
Honda CB1000 CB900 master cylinder reservoir cap plastic o-ring 45521-MJ6-006

Honda CB Master Cylinder Reservoir Cap Plastic O-Ring ~ Replaces 45521-MJ6-006

$4.95 USD
29-0062
Replace your master cylinder cap O-ring with this Master Cylinder Reservoir Cap Plastic O-Ring, replacing OEM #45521-MJ6-006.Key Features• Master cylinder reservoir cap O-ring• Plastic•...
Honda CB1100 CB1000 CB900 master cylinder reservoir cap 45513-341-771

Honda CB Master Cylinder Reservoir Cap ~ Replaces 45513-341-771

$39.95 USD
29-0054
Restore your master cylinder cap with this Master Cylinder Cap with Plastic O-Ring, replacing OEM #45513-341-771. This original style was discontinued long ago by...
Universal Honda-type front master cylinder assembly 13mm

Universal Honda-Type Front Master Cylinder Assembly ~ 13mm

$84.95 USD
08-0262
Upgrade to a universal front master cylinder assembly with this Honda-type unit. Complete with lever, banjo bolt, banjo bolt washers, and brake light switch,...
Honda CB750A CB750K rear brake light switch spring 35357-393-000

1976-78 Honda CB750A / CB750K Rear Brake Light Switch Spring ~ Replaces 35357-393-000

$5.80 USD
73-1006
Replace your rear brake stop switch spring with this Rear Brake Light Stop Switch Spring. This is the spring that attaches to the rear...
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Honda CB750 CB650 CB550 replacement brake lever for master cylinder

Honda CB Replacement Brake Lever for Master Cylinder 08-0262

$9.95 USD
08-0430
Replace the brake lever on the #08-0262 Master Cylinder Assembly specifically with this Brake Lever. Designed for this particular master cylinder.Key Features• Replacement brake...
Honda CB1100 CB1000 CB900 master cylinder reservoir cap 43513-MJ6-006

Honda CB Master Cylinder Reservoir Cap ~ Replaces 43513-MJ6-006

$23.45 USD
29-0080
Replace your master cylinder reservoir cap with this Master Cylinder Reservoir Cap with Diaphragm, round OEM thread-on type. Cap replaces OEM #43513-MJ6-006, diaphragm replaces...
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Honda CB750 replacement brake lever for master cylinder 08-0253

Replacement Brake Lever for Master Cylinder 08-0253

$9.95 USD
08-0029
Replace the brake lever on the #08-0253 Master Cylinder Assembly specifically with this Brake Lever. Designed for this particular master cylinder, not stock brake...
Magura universal front master cylinder assembly 13mm

Magura Universal Front Master Cylinder Assembly ~ 13mm

$259.00 USD
08-0250
Build a custom front brake setup with this Magura Universal Front Brake Master Cylinder. Features a 13mm piston diameter, 12mm stroke, and a threaded...
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1978 Honda CB750K · Master Cylinder & Rebuild Parts Buying guide

Check the fitted unit and brake-light arrangement

The rebuild kit names reference 45530-404-315. Reservoir cap and diaphragm products are separate choices, and replacement assemblies need their own specification and brake-light requirement checked before purchase.

Parts to consider

Honda CB Front Master Cylinder Rebuild Kit ~ Replaces 45530-404-315 Front master cylinder rebuild kitListed against Honda reference 45530-404-315 for the 1977–78 CB750K application. Compare the existing unit before rebuilding.View part Honda CB Master Cylinder Reservoir Diaphragm ~ Replaces 45520-300-000 Reservoir diaphragmSeparate front reservoir diaphragm product references Honda 45520-300-000 for the stated CB750K application.View part Honda CB Master Cylinder Reservoir Cap ~ Replaces 45513-341-771 Reservoir cap with plastic O-ringCap package names Honda reference 45513-341-771 and lists a plastic O-ring. A diaphragm is a separate product.View part

Compare the offered piston sizes before choosing an assembly

Stock-look assembly 08-0253 lists a 5/8-inch piston, while 08-0269 lists 14 mm. These are specifications of the offered replacements, not independent confirmation of the motorcycle’s original bore. Have the fitted braking system and chosen assembly checked for suitability before ordering.

Match rebuild parts to the actual master cylinder

The model-specific rebuild kit has its own Honda reference. An aftermarket or previously replaced master cylinder may have different internals and reservoir parts. Identify the fitted unit, then compare its application before selecting the kit, cap or diaphragm from this category.

Common questions

Which stock-look replacement assemblies require a separate brake-light switch for the 1978 K?

Both 08-0253 and 08-0269 explicitly require hydraulic brake-light switch 29-7002 for their 1978 CB750K application. Compare that requirement with the installed brake-light arrangement before ordering; similar exterior styling does not mean the switch is supplied.

How do the two reservoir-cap packages differ?

The featured 29-0054 cap replaces 45513-341-771 and includes a plastic O-ring. Cap 29-0080 replaces 43513-MJ6-006 and instead lists a diaphragm replacing 45520-300-000. Compare the fitted reservoir and needed sealing pieces before selecting by the shared cap name.

Can the cap’s plastic O-ring be replaced without buying another cap?

The separate plastic O-ring listing, part 29-0062, replaces 45521-MJ6-006 and includes the CB750K application. Compare that component with the retained cap and reservoir before choosing the limited repair. The reservoir diaphragm is a different separately identified piece.

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