How to Bleed and Replace Brake Fluid on a 1987 Honda TRX350 4X4
Shop parts for a 1987 Honda TRX350 4X4 ATV.
This MotoSport-exclusive guide walks you through flushing and bleeding the hydraulic brakes on a 1987 Honda TRX350 4X4, plus model-specific notes every owner should know. Follow these steps exactly to restore firm pedal feel and prevent contamination or damage to legacy brake components.
Tools & supplies
- DOT 3 or DOT 4 brake fluid (DOT 3 recommended for original systems)
- Brake bleeder kit or clear tubing and a catch bottle
- Open-end wrenches (8mm-12mm assortment)
- Phillips & flat screwdrivers
- Brake parts cleaner and rags
- Jack or stands to access wheels if needed
- Protective gloves & eye protection
- Vacuum bleeder or one-way bleeder fittings (optional but speeds the job)
Model notes & things to know about the 1987 TRX350 4X4
- The TRX350 was built with a relatively simple, small-capacity master cylinder reservoir. Keep the cap on except when actively topping or replacing fluid to avoid rapid contamination.
- Factory lines and fittings on 1987 models may be aged or corroded. Inspect rubber hoses and metal fittings for swelling, cracking, rust, or leaks before bleeding. Replace any compromised lines rather than simply bleeding through them.
- Older TRX350 calipers and bleeder screws can be fragile from corrosion. Apply penetrating lubricant and work gently to avoid rounding off screws.
- Some TRX350s left the rear as a sealed drum or had different hardware depending on aftermarket changes over the years. Confirm whether you have rear disc caliper bleeders or a drum brake system before starting.
- Use only DOT-designated brake fluids. Do not use mineral-oil-based systems or mix with DOT fluid.
Preparation
- Park the ATV on level ground, block wheels, and secure the parking brake if present. Remove the seat or body panels needed to access the master cylinder reservoir and the calipers/bleeders.
- Clean the master cylinder cap area to keep dirt from entering the system. Remove the cap and diaphragm, leaving the reservoir open only as long as necessary.
- Identify the master cylinder location and the brake line routing to determine the distance order to each wheel. The general bleeding order is farthest wheel from the master cylinder first and the closest last.
Drain & replace brake fluid (full flush)
- Use a turkey-baster or siphon to remove as much old fluid from the master reservoir as possible without pulling air into the system.
- Top the reservoir with fresh DOT 3 brake fluid to the recommended level.
- Begin at the farthest brake caliper or wheel cylinder from the master cylinder. Fit clear tubing over the bleeder screw and submerge the other end in a catch bottle partially filled with clean fluid to prevent air being drawn back in.
- Have an assistant slowly depress the brake pedal several times and hold it down. Crack the bleeder screw slightly until fluid runs with bubbles; then tighten the screw and release the pedal. Repeat until clear fluid with no bubbles emerges. Keep the master reservoir topped between cycles to avoid drawing air into the master cylinder.
- Move to the next-farthest wheel and repeat the process. Finish at the wheel nearest the master cylinder.
- For drum-style rear brakes: if the model uses a wheel cylinder with a bleed screw, treat it like a caliper. If rear drums are purely mechanical, you won't have hydraulic bleeders at the druminspect and service accordingly.
One-person or vacuum bleeding method (if working solo)
- Use a vacuum bleeder on the bleeder screw or a piston-type hand pump attached to the master cylinder. Pump until clear fluid flows without bubbles, keeping the reservoir topped.
- Alternatively, install a one-way bleeder fitting that allows fluid out but prevents air back in; then pump the brakes slowly until fluid clears.
Finishing steps & checks
- After all lines are bled, tighten bleeder screws to a snug fit. Wipe all fittings and check for leaks.
- Top the master cylinder to the proper level, reinstall the cap and diaphragm, and secure any panels or the seat removed earlier.
- Pump the brake pedal with the ATV still supported until firm pedal pressure is achieved. If the pedal remains spongy, repeat bleeding focusing on the most distant points and the master cylinder.
- Dispose of old brake fluid safely — it is hygroscopic and corrosive.
Troubleshooting
- Spongy pedal after bleeding: likely air still trapped or a leak. Recheck bleed order, and inspect lines, fittings, and the master cylinder for internal leaks.
- Bleeder screw rounded or stuck: apply penetrating oil, allow time to soak, then use a correct-size wrench. Heat is not recommended on rubber-lined systems.
- Continuously low fluid level after bleed: indicates external leak or internal master cylinder failure do not continue to operate until diagnosed.
Maintenance interval & recommendations
- Replace brake fluid every 1-2 years to avoid moisture build-up and corrosion in the 1987 TRX350 system.
- Inspect rubber hoses and connections annually, especially on older machines that see wet or salty environments.
- When replacing hoses or fittings, use OEM-quality parts or MotoSport-approved replacements to maintain correct pressure ratings and compatibility with DOT fluids.
Follow this MotoSport procedure and your vintage TRX350 will maintain safe, reliable braking. For parts, lines, bleeder fittings, or replacement reservoir caps specific to the 1987 TRX350 4X4, visit our parts page above to get OEM-grade components tailored to this model.
Related Shopping Categories
Shop Brake Fluid for a 1987 Honda TRX350 4X4 ATV.
Shop Brake Bleeders for a 1987 Honda TRX350 4X4 ATV.
Shop Brake Pads for a 1987 Honda TRX350 4X4 ATV.
Shop Brake Lines for a 1987 Honda TRX350 4X4 ATV.
Shop Brake Tools for a 1987 Honda TRX350 4X4 ATV.
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.