How To Bleed 1993 Honda CB750 - Nighthawk Motorcycle Brakes

Bleeding the Brakes on a 1993 Honda CB750 Nighthawk

What This Nighthawk’s Brake System Looks Like

The 1993 Honda CB750 Nighthawk uses hydraulic disc brakes at both ends. The front brake is operated by the lever on the right handlebar and the rear brake by the foot pedal, and each has its own master cylinder and fluid reservoir. This bike is not equipped with ABS or a linked brake system, so the front and rear circuits are independent and the bleeding work stays at the caliper bleeder valves. The rear brake is a hydraulic disc, not a mechanical drum, so it uses brake fluid and needs to be bled just like the front. That makes this a two-circuit job: bleed the front, then bleed the rear, keeping each reservoir topped off as you go.

When a Bleed Is Due—and Why It Matters

A brake bleed is part fluid refresh and part air removal. The lever or pedal should feel firm and consistent. If the front lever feels spongy, pulls closer to the grip than it used to, or slowly sinks under steady pressure, air is likely in the system. The same goes for a rear pedal that feels soft or travels farther than normal. Dark or cloudy fluid in either reservoir is another sign that old fluid has been in service too long. A bleed is also due after any work that opened the hydraulic system, such as new brake lines, caliper service, or master cylinder work.

Even when the brakes feel fine, brake fluid absorbs moisture from the air over time. Moisture lowers the fluid’s boiling point, and under hard or repeated braking that can lead to brake fade. Many riders refresh the fluid on a regular schedule as preventive maintenance rather than waiting for a soft lever. On a bike like this Nighthawk, where the front and rear systems are separate, it is worth checking both reservoirs at the same time so one circuit does not get overlooked.

Gather the Right Supplies Before You Start

• Fresh brake fluid of the type marked on the master cylinder reservoir cap, from a sealed container
• A box-end wrench that fits the bleeder valve
• A length of clear tubing that fits snugly over the bleeder
• A catch bottle for the old fluid
• Rags or shop towels
• A syringe or turkey baster for removing old fluid from the reservoir
• A screwdriver or driver that fits the reservoir cap screws

A one-way check-valve bleeder or a vacuum bleeder can make the job easier for one person, but the manual lever-and-bleeder method works fine with a little patience. Keep the fluid container capped when you are not pouring from it, and do not reuse fluid that has been sitting open or drained out of the system.

Set Up the Bike and Protect the Finish

Support the Nighthawk securely upright on a stand so it cannot tip while you are working the lever or pedal. For the front circuit, turn the handlebars so the front reservoir sits level before you remove the cap. For the rear circuit, make sure the rear reservoir is also level; on this bike it is not at the handlebar, so check its mounting position before opening it. Cover painted surfaces, plastic bodywork, and the instrument area with rags, because most brake fluids damage paint and plastic on contact. If a spill happens, wipe it up immediately and rinse the area with water. Do not let fluid sit on the finish while you finish the job.

Step-by-Step Bleeding Procedure

1. Start with the front circuit. Remove the reservoir cap and diaphragm, then use the syringe or turkey baster to remove most of the old fluid from the reservoir. Leave enough fluid in the bottom so you do not push air into the master cylinder.
2. Refill the reservoir with fresh fluid of the type marked on the cap. Keep the container sealed when you are not pouring.
3. Fit the clear tubing over the front caliper bleeder valve and route the other end into the catch bottle. The tubing should fit snugly so air cannot be drawn in around it.
4. Slide the box-end wrench onto the bleeder valve. Squeeze the front lever and hold it steady, then open the bleeder about a quarter turn. Fluid and air will move out through the tube.
5. Close the bleeder before you release the lever. Releasing the lever with the bleeder open can draw air back into the caliper.
6. Repeat the squeeze-hold-open-close-release sequence, checking the reservoir level often and topping it off before it gets low. Never let the reservoir run dry enough to draw air into the master cylinder.
7. Continue until fresh, clean fluid comes through the tube with no bubbles. On a system with more than one caliper on a circuit, start with the caliper farthest from the master cylinder and bleed each one in turn; on this Nighthawk each circuit has one caliper, so you bleed the front, then move to the rear.
8. Move to the rear circuit. Remove the rear reservoir cap and diaphragm, remove most of the old fluid, and refill with fresh fluid. Attach the clear tubing to the rear caliper bleeder and route it to the catch bottle.
9. Press and hold the rear pedal, open the rear bleeder about a quarter turn, then close it before releasing the pedal. Repeat until the fluid runs clean and bubble-free, topping off the rear reservoir as needed.
10. When both circuits are done, top each reservoir to the correct level marking, reinstall the diaphragm and cap, and wipe up any spilled fluid.

Finishing the Job and Checking for Leaks

Tighten each bleeder valve snugly with the box-end wrench, but do not overtighten it. A bleeder only needs to be closed firmly enough to seal; forcing it can damage the seat. Check the bleeder valves and the banjo fittings at the master cylinders and calipers for weeping or wetness. A dry fitting after several lever or pedal applications is what you want to see. Reinstall the reservoir diaphragms and caps completely, and make sure the caps seat evenly so fluid cannot splash out. Clean any residue from the calipers, lines, and bodywork before you test the brakes.

Test Before You Ride

The front lever and rear pedal should feel firm and consistent, not spongy, and they should not slowly sink while you hold steady pressure. Spin each wheel by hand to confirm the brakes are not dragging; a wheel that stops quickly or feels tight may mean a caliper is not releasing or the fluid level is wrong. With the bike upright and in a safe area, test the brakes at low speed before riding normally. Start with the front, then the rear, and make sure both slow the bike smoothly and predictably.

If Something Does Not Feel Right

If the lever or pedal will not firm up after several bleeding attempts, or if it firms up only after pumping, stop and look for the cause rather than continuing to pump fluid through. Persistent air bubbles, fluid leaking from the master cylinder or caliper, or a lever that still feels soft after a careful bleed are signs that the job may need a shop’s attention. Because this Nighthawk does not have ABS or linked brakes, the procedure is straightforward, but a system that will not hold pressure should not be ridden until it is sorted out. If you are unsure whether air has entered the system or you cannot get a firm lever, have the bike inspected before your next ride.

Related Shopping Categories

Shop Brake Fluid for a 1993 Honda CB750 - Nighthawk Motorcycle.

Shop Brake Lines for a 1993 Honda CB750 - Nighthawk Motorcycle.

Shop Brake Pads for a 1993 Honda CB750 - Nighthawk Motorcycle.

Shop Stands for a 1993 Honda CB750 - Nighthawk Motorcycle.

Shop Brake Tools for a 1993 Honda CB750 - Nighthawk Motorcycle.

Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your motorcycle's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.