Bleeding the Brakes on a 2016 KTM RC 390
Shop parts for a 2016 KTM RC 390 Motorcycle.The 2016 KTM RC 390 uses hydraulic disc brakes at both ends and is equipped with ABS. That means routine brake bleeding follows the familiar caliper-bleeder procedure, but the ABS unit adds one important caveat: if air has entered the ABS hardware itself, a home bleed may not be enough. This guide walks through a normal fluid refresh and air bleed at the calipers, with clear stopping points for when the bike should go to a shop.
When the RC 390 Needs a Brake Bleed
Bleed the brakes when the front lever or rear pedal feels spongy, when the lever pulls closer to the grip than it used to, or when the fluid in either reservoir looks dark or cloudy. 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 without symptoms, brake fluid absorbs moisture over time, which lowers its boiling point and can contribute to fade under hard use, so many riders refresh it on a regular schedule.
On this bike, treat the front and rear as separate hydraulic circuits. The ABS system is not a reason to skip a routine caliper bleed, but it is a reason to be careful about letting the reservoirs run dry. If the reservoir has gone empty, the ABS unit or its lines have been disconnected, or you suspect air is trapped inside the ABS hardware, stop and have the bike serviced with the appropriate dealer-level procedure or diagnostic tool.
Tools and Supplies to Have Ready
- 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 snugly
- Clear tubing that fits tightly over the bleeder valve
- A clean catch bottle for old fluid
- Rags or shop towels, plus 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 when working alone, but the manual lever-and-bleeder method works fine if you have a helper or a check valve. Use only fluid from a sealed container, and do not mix fluid types.
Prepare the Bike and Protect the Finish
Support the RC 390 securely upright on a stand so it cannot tip while you are working the lever or pedal. Turn the handlebars so the front reservoir sits level before you open it. Cover painted surfaces, plastics, 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.
Before opening the reservoir, clean around the cap so dirt does not fall in. Remove the cap and diaphragm, then use the syringe or turkey baster to remove most of the old fluid from the reservoir. Do not let the reservoir run dry at any point during the job; keeping fluid above the low mark is what keeps air from being drawn into the system.
The Bleeding Procedure: Front and Rear
- Refill the front reservoir with fresh fluid to the correct level marking, then set the cap loosely in place to keep debris out.
- Push the clear tubing onto the front caliper bleeder valve and route the other end into the catch bottle with a small amount of fluid in the bottom.
- Squeeze and hold the front lever firmly. While holding it, open the bleeder about a quarter turn and let fluid and air escape through the tube.
- Close the bleeder before releasing the lever. Releasing with the bleeder open can draw air back into the caliper.
- Repeat the squeeze-hold-open-close-release sequence, topping off the reservoir as needed, until fresh, clean fluid with no bubbles comes through the tube.
- When a circuit has more than one caliper, start with the caliper farthest from the master cylinder and work through the others one at a time. On a single-caliper circuit, work at that caliper.
- Move to the rear brake. Refill the rear reservoir, attach the clear tubing to the rear caliper bleeder, and press and hold the pedal instead of the lever.
- Open the rear bleeder about a quarter turn while holding the pedal, close it before releasing the pedal, and repeat until the fluid runs clean and bubble-free. Keep the rear reservoir topped off throughout.
Finish the Job and Check for Leaks
Once both circuits run clean, tighten each bleeder snugly without overtightening. Fill each reservoir to the correct level marking, reinstall the diaphragm and cap, and clean any spilled fluid from the calipers, lines, and reservoir area. Check for leaks at the bleeder valves and at the banjo fittings. A dry fitting after several lever or pedal applications is a good sign; a wet fitting needs attention before the bike is ridden.
Test Before Riding and Know When to Stop
The front lever and rear pedal should feel firm and consistent, not spongy, and they should not slowly sink under steady pressure. Spin each wheel to confirm the brakes are not dragging. Test the brakes at low speed in a safe area before riding normally.
If the lever will not firm up after several bleeding attempts, if it firms only after pumping, if bubbles keep appearing, or if fluid leaks from the master cylinder or caliper, stop and diagnose the problem. Because this RC 390 is ABS-equipped, any sign that air entered the ABS unit itself is a shop-level concern. A firm, clean, leak-free system is the only result worth riding on.
Related Shopping Categories
Shop Brake Fluid for a 2016 KTM RC 390 Motorcycle.
Shop Brake Lines for a 2016 KTM RC 390 Motorcycle.
Shop Brake Pads for a 2016 KTM RC 390 Motorcycle.
Shop Stands for a 2016 KTM RC 390 Motorcycle.
Shop Brake Tools for a 2016 KTM RC 390 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.
