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1970 Honda CB450K Master Service Kits, Caps & Diaphragms

Identify the master cylinder retained on your 1970 CB450K before choosing a service kit, reservoir cap or diaphragm. These products describe different repair components. Compare their references and supplied contents first; a universal replacement master requires a separate assessment of the custom hydraulic installation.

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Currently viewing Master Cylinder & Rebuild Parts

Honda motorcycle parts

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Honda CB750 CB550 CB400F front master cylinder kit 45530-377-305

Honda CB Front Master Cylinder Rebuild Kit ~ Replaces 45530-377-305

$37.95 USD
08-0215
Rebuild your early SOHC CB's front master cylinder with this Front Brake Master Cylinder Rebuild Kit, replacing OEM #45530-377-305. Made in Japan. Fits the...
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...
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 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,...
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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...
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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1970 Honda CB450K · Master Cylinder & Rebuild Parts Buying guide

Match the master and compare each reservoir package

The rebuild kit references Honda 45530-377-305 without a detailed components list. One round cap includes a diaphragm; another cap includes a plastic O-ring. The separate diaphragm and brake-hose junction boot serve distinct locations and need comparison with the retained assembly.

Parts to consider

Honda CB Front Master Cylinder Rebuild Kit ~ Replaces 45530-377-305 Front master cylinder service kitRebuild kit referencing Honda 45530-377-305 and listed for the 1970 CB450K. Match the installed master before choosing it. The description does not itemize the seals and other components supplied in the kit.View part Honda CB Master Cylinder Reservoir Cap ~ Replaces 43513-MJ6-006 Round cap with diaphragmRound thread-on reservoir cap referencing Honda 43513-MJ6-006, supplied with a diaphragm referencing 45520-300-000. Compare the reservoir and retained cap before selecting this cap-and-diaphragm repair.View part Honda CB Master Cylinder Reservoir Diaphragm ~ Replaces 45520-300-000 Separate reservoir diaphragmDiaphragm referencing Honda 45520-300-000. Check the reservoir and cap assembly being retained. It is a separate component; another cap choice shown here explicitly includes a diaphragm.View part

Related parts: Cap with plastic O-ring · Brake-hose junction rubber boot · Universal 13mm master comparison

Choose the cap repair without duplicating its contents

The round thread-on cap references 43513-MJ6-006 and includes diaphragm 45520-300-000. The separate diaphragm uses that same reference. The other cap references 45513-341-771 and lists a plastic O-ring. Compare the retained reservoir and choose from the stated package rather than assuming all cap contents are identical.

Keep universal replacement requirements separate

The Honda-type universal master includes lever, banjo hardware and switch, with a 13mm bore and right-hand-threaded mirror mount. The Magura lists a 13mm piston, 12mm stroke, separate switch and banjo hardware, and no mirror mount. Confirm suitability for the custom system; the Honda rebuild-kit application does not prove that kit fits either universal master.

Practical parts selection questions

Can I order the service kit expecting a specific internal seal?

The rebuild-kit description gives reference 45530-377-305 but does not itemize its individual components. Confirm the contents if a particular seal is essential to the repair. The photograph should not be used to invent a detailed piece list or compatibility with a different master.

Does the cap with a plastic O-ring also list a diaphragm?

That cap description names a plastic O-ring, without itemizing a diaphragm. The round cap with reference 43513-MJ6-006 explicitly includes diaphragm 45520-300-000. Compare the actual cap and reservoir arrangement before choosing or adding a separate diaphragm.

Can the hose-junction boot replace the reservoir diaphragm?

The boot references 45522-300-010 and is described where the brake hose joins the master cylinder. The diaphragm references 45520-300-000 in the reservoir assembly. Match the location needing renewal; their separate functions and references do not establish interchange.

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