R-77 End Cap Kit Replacement: Left Side Flared Guide

By Yoshimura R&D of America, Inc. | Published: 2026-10-26

Category: How-to Guides

Step-by-step instructions to replace the left side flared end cap on your Yoshimura R-77 muffler using the R-77 Replacement End Cap Kit. Includes common mistakes to avoid.

Quick answer

Replace the left side flared end cap on your Yoshimura R-77 muffler using the R-77 Replacement End Cap Kit. The kit includes a carbon fiber cap, rivets, rivet band, and grommet—no special tools beyond a hand riveter and a drill are needed.

What the kit includes and why it matters

The R-77 Replacement End Cap Kit (left side, flared outlet) comes with a high-gloss lightweight carbon fiber end cap, rivets, a rivet band, and an insert hole grommet. All parts are made in Yoshimura's composites shop in Chino, California, using heat-resistant impregnated carbon fiber. This means the cap is built to handle exhaust temperatures without degrading over time.

If you are unsure which end cap fits your muffler, check the outlet shape (flared vs. straight) and the side (left vs. right). The kit only fits R-77 left side mufflers with a flared outlet. Using the wrong cap may not seal properly or align with the rivet holes.

Before you start: check your current cap and tools

You will need a hand riveter, a drill with a bit slightly smaller than the rivet heads (typically 1/8 inch), and a flat screwdriver or punch to remove old rivets. Safety glasses are recommended when drilling.

Inspect the existing end cap for cracks or deformation. If the muffler body or mounting bracket is damaged, replacing only the end cap may not solve the issue. The kit is for cosmetic or minor damage to the cap itself.

Step-by-step replacement

Remove the old end cap: Drill out the rivets holding the old end cap to the muffler body. Use a drill bit slightly smaller than the rivet head to avoid enlarging the holes. After drilling, push the rivet remnants out with a punch or screwdriver. Common mistake: drilling too deep or using a bit that is too large can damage the muffler shell. Stop as soon as the rivet head pops off.
Clean the mounting surface: Wipe the inside of the muffler outlet and the area where the new grommet will sit. Remove any debris or old sealant. A clean surface helps the new cap seal properly and prevents rattles.
Install the new grommet and rivet band: Place the new insert hole grommet into the muffler outlet. Then slide the rivet band over the grommet so the holes align with the muffler's rivet holes. The band holds the grommet in place during riveting. Check that the grommet is fully seated and not twisted. A misaligned grommet can cause exhaust leaks.
Attach the new end cap: Position the new carbon fiber end cap over the rivet band. Insert the supplied rivets through the cap, band, and muffler holes. Use a hand riveter to pull each rivet until it snaps. Work in a cross pattern (e.g., top-left, bottom-right) to ensure even pressure. Common mistake: over-tightening rivets can crack the carbon fiber. Stop pulling as soon as the rivet mandrel breaks.
Inspect the fit and test for leaks: After all rivets are installed, gently tug on the cap to confirm it is secure. Start the engine and listen for any exhaust noise escaping around the cap edges. A small puff of smoke is normal during first heat cycle, but a steady leak means a rivet is loose or the grommet is misaligned. If you hear a leak, let the muffler cool, then re-check rivet tightness and grommet position before re-riveting.

Product facts

R-77 REPLACEMENT END CAP KIT FLARED LEFT SIDE: Fits R-77 LEFT Side mufflers with a flared outlet. Made in our composites shop in Chino, California with heat resistant impregnated, high gloss lightweight carbon fiber. This ensures the cap withstands exhaust heat and matches the left side flared outlet geometry, preventing fitment issues.
R-77 REPLACEMENT END CAP KIT FLARED LEFT SIDE