Yoshimura 12122 Muffler Bracket Spacer: Function and Replacement Guide

Quick answer

The Yoshimura 12122 muffler bracket spacer sits between the muffler bracket and the frame or subframe mount, holding the exhaust at the correct offset so the can, mid-pipe, and header stay aligned under vibration. Replace it when it is crushed, missing, cracked, or when the muffler no longer sits square in its bracket. Always install it with the correct bolt length and torque, and check clearance before you ride.

A muffler bracket spacer is one of those small parts you never think about until it is gone. On Yoshimura systems, the 12122 spacer sets the gap between the muffler bracket and the mounting point, which keeps the exhaust can positioned correctly instead of pulled tight against the frame or hanging at an angle.

This guide walks through what the spacer does, how to recognize a worn or missing one, and an ordered replacement process you can do in a garage with basic hand tools. If you are also chasing a rattle or a misaligned can, pair this with a full hardware check rather than replacing the spacer alone.

What the 12122 spacer actually does

The spacer is a precise offset piece. It fills the gap between the muffler bracket and the mounting tab so the bracket bolts down flat instead of being distorted. That matters because a bracket pulled out of shape changes the angle of the muffler, which can load the mid-pipe joint and the header flange in ways they were not designed for.

It also isolates the joint from vibration. A spacer that is crushed, ovalized, or missing lets the bracket and frame rub directly, which shows up as a rattle at idle, a buzz at certain RPM, or paint and metal wear around the mount. If your exhaust moved after a tip-over or a hard landing, inspect this spacer before you assume the whole system is bent.

• Check the spacer any time you remove the muffler for packing, cleaning, or a tire change.
• A missing spacer is often the real cause of a rattle that sounds like it is coming from inside the can.

Signs the spacer needs replacement

The most common sign is visual: the spacer is squashed, cracked, or has a worn lip where it contacts the bracket. You may also see a shiny wear mark on the frame or subframe where metal has been rubbing metal. If the muffler can is no longer centered in its bracket, or the bracket has to be forced into place, the spacer is likely the wrong thickness or has deformed.

A second sign is hardware behavior. If the mounting bolt bottoms out before the bracket is snug, or if you have to add washers to take up a gap, the original spacer is doing its job poorly or is gone. Do not stack random washers as a permanent fix; they shift under vibration and can loosen.

• Photograph the mount before disassembly so you can confirm the spacer goes back in the same position.
• If the bolt threads show galling or the spacer is seized to the bolt, replace both rather than reusing them.

Tools and parts to have ready

You need the replacement spacer, the correct mounting bolt, and a torque wrench that covers the small values used on exhaust hardware. A socket set, a hex key set, and a torque wrench are usually enough. Penetrating oil helps if the bolt has seen rain, mud, or winter salt. A soft mallet and a pick can help free a seized spacer without damaging the bracket.

Before you start, confirm you have the right part for your system. Yoshimura sells small components individually, including spacers and mounting hardware, and the support line can confirm fitment if the listing is unclear. Have your bike model and exhaust model on hand when you call or email.

• Work on a cold exhaust. Metal expands when hot and you risk burning yourself or stripping threads.
• Use a torque wrench, not feel. Exhaust bolts are small and easy to overtighten.

Removing the old spacer without damaging the bracket

Support the muffler with a stand or a block before you remove the mounting bolt. Once the bolt is out, the can can drop or swing, which strains the mid-pipe joint. With the weight supported, remove the bolt and slide the old spacer out. If it is stuck, apply penetrating oil and work it free with a pick rather than prying against the bracket.

Inspect the bracket and the frame tab while the spacer is out. Look for cracks, elongated bolt holes, or a bent tab. A bent bracket will keep eating spacers until it is straightened or replaced, so address that before installing a new one.

• Do not let the muffler hang from the mid-pipe. Support it before removing the mount bolt.
• If the bracket hole is ovalized, a new spacer will not fix the alignment problem.

Installing the new spacer and checking alignment

Slide the new spacer into position, align the bracket and frame tab, and start the bolt by hand. Thread it in most of the way by hand before you apply a wrench. Snug the bolt, then check that the muffler sits square, the can is centered in the bracket, and there is clearance between the exhaust and the plastics, swingarm, or tire.

Torque the bolt to the specification for your system. If you do not have the spec, tighten in small increments and stop when the bracket is secure with no gap and no deformation. Overtightening crushes spacers and can crack tabs. After the first ride, recheck the bolt and the spacer position, because heat cycles can settle the joint.

• Push and pull the muffler by hand after torquing. It should feel firm with no clunk or side-to-side play.
• Recheck torque after the first heat cycle and again after the first ride.

Spacer replacement steps

1. Support the muffler, then loosen the mount: Place a stand or block under the can so it cannot drop when the bracket bolt comes out. Remove the mounting bolt and slide the old spacer free. Mistake to avoid: letting the muffler hang from the mid-pipe, which strains the joint and can crack it.
2. Inspect the bracket, tab, and bolt: Look for cracks, elongated holes, a bent tab, or a stretched bolt. Clean any corrosion or road grit off the mounting faces. Checkpoint: if the bracket is bent or the hole is ovalized, fix that first or the new spacer will not hold alignment.
3. Fit the new spacer and start the bolt by hand: Slide the replacement spacer into place, line up the bracket and frame tab, and thread the bolt in by hand until it seats. Mistake to avoid: forcing the bolt with a wrench before it is threaded straight, which cross-threads the tab.
4. Torque to spec and check clearance: Tighten to the specification for your system, then confirm the can is centered and there is clearance to plastics, swingarm, and tire. If you do not have a torque spec, tighten in small increments and stop before the spacer or tab deforms.
5. Recheck after the first heat cycle: Let the exhaust cool after a short ride, then recheck bolt torque and spacer position. Next step: if the rattle returns, inspect the other mounting points and the mid-pipe joint before replacing the spacer again.

Genuine Yoshimura parts that support this job

• 8mm x 12mm Aluminum Spacer: Yoshimura sells small system components individually, including spacers, rivets, rivet bands, nuts, bolts, and grommets. You can replace a single worn spacer instead of buying a whole bracket or hardware kit, which keeps a small repair inexpensive.
• RUBBER WASHER, 3/8": Yoshimura offers small hardware pieces for its systems, and support can help identify the right one if the listing is unclear. If your mount uses a rubber washer alongside the spacer, replacing a hardened or missing washer at the same time prevents a new rattle.
• CRF450R 2005 Stainless Header: Yoshimura offers replacement headers because the header is often the component that takes the beating from roost and impacts. If a bad spacer let the system shift and the header is now dented or cracked, a replacement header gets the bike back on the trail.

The 12122 spacer is a small part with a real job: it holds your muffler bracket at the right offset so the whole system stays aligned and quiet. Replace it when it is crushed, missing, or letting the can move, and always support the muffler, torque the bolt properly, and recheck after the first ride. If you are unsure which spacer or hardware your system uses, contact Yoshimura support with your bike and exhaust model before you order.