How to Bleed Yamaha YFZ450R Brakes

Just like on any other vehicle, the brakes on a Yamaha ATV will wear down over time. If the brakes on your ATV feel worn, sometimes a simple brake bleed is all they need.

Check the brake fluid to see if it’s dark and viscous and if so, it’s time for a brake bleed. Watch the video above and follow the steps below to bleed the brakes on a Yamaha YFZ450.

Tools and Supplies - Yamaha YFZ450 Brake Bleed

NOTE: We bled the brakes on a Yamaha YFZ450R, but the steps to bleed the brakes on a YFZ450 are the same or similar for all Yamaha ATVs. 


Yamaha Dot 4 brake fluid

Impact driver

Yamaha YFZ450 Brake Bleed

Step 1. Remove the cover from the front master cylinder reservoir. Next, remove the plastic section and the rubber diaphragm below the cover and clean them off. 

Yamaha YFZ450 master cylinder

PRO TIP: If the screws don’t come off right away with a regular Phillips screwdriver, use an impact driver instead.

Step 2. Connect one end of a length of hose to the bleed valve, and have the other end ready to drain into an empty container. 

YFZ450 brake bleed

Step 3. Pump and then hold the right-side brake handle, open the valve until it bottoms out, then close the valve and repeat. 

Yamaha YFZ450 brake bleeding

NOTE: Keep an eye on the reservoir as you're doing this to avoid forcing an air bubble down into the caliper.

Step 4. Repeat step 3 around 20-25 times as you pour brake fluid into the reservoir.

Yamaha Dot 4 brake fluid

Step 5. Once the right side is filled up, tighten up the valve and repeat Steps 3-4 for the left side. 

Yamaha ATV brake bleed

NOTE: Make sure to put the dust and dirt cap back on both sides after tightening the valve.

Step 6. Check the sight level on the reservoir before refilling the brake fluid to avoid overfilling it.

Yamaha YFZ450 brake fluid reservoir

Step 7. Once the reservoir is filled up to the sight level (don’t fill it all the way to the top), replace the diaphragm, the plastic spacer and the cover in that order. 

Yamaha ATV brake fluid reservoir

Step 8. Locate the rear reservoir under the seat and remove the cap, spacer and diaphragm. 

Brake bleed Yamaha YFZ450

Step 9. Top off the rear reservoir with new brake fluid, then pump out the old brake fluid several more times to flush it out. Make sure not to overfill the reservoir before replacing the diaphragm, spacer and cap.

Yamaha YFZ450R ATV brake bleed

As noted, the steps to bleed the brakes on a YFZ450 are the same or similar for all Yamaha ATVs. However, if you want to see a brake bleed for a different Yamaha ATV model, watch the video below to see how to bleed the brakes on a Yamaha Grizzly 700.



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