RS-12 Full Exhaust on the CRF450R: Install and Fit FAQ

Quick answer

Install the RS-12 full exhaust by first confirming your bike is a 2021-2024 CRF450R/RX or 2023-2024 CRF450R-S, then remove the stock system, test-fit the stainless header and muffler without tightening, and torque all mounts only after checking clearance at the shock, engine case, and plastics.

Step-by-step RS-12 full exhaust install

1. Confirm your model year and model: Check the VIN or model plate to confirm your bike is a 2021-2024 CRF450R/RX or a 2023-2024 CRF450R-S. Common mistake: assuming all CRF450 variants share the same exhaust layout. If your bike is outside these years, do not proceed.
2. Remove the stock exhaust in order: With the engine cold, disconnect the muffler mount, then the header flange nuts, and slide the stock system out as one unit. Common mistake: forcing the header out before the muffler is free, which can bend a flange. Keep the stock flange nuts and any gaskets for inspection.
3. Inspect and prepare the head pipe flange: Clean the exhaust port surface and check the stock gasket. If it is crushed or damaged, replace it. Common mistake: reusing a hardened gasket, which causes a leak that sounds like a tick. A new gasket is cheap insurance against a header leak.
4. Test-fit the RS-12 header and muffler loosely: Slide the header into the port and fit the muffler to the header joint and frame mounts without tightening anything. Common mistake: tightening the header first, which pulls the muffler out of alignment. All bolts should be finger-tight until clearance is checked.
5. Check clearance at the shock, engine case, and plastics: Look for at least a finger-width gap at the rear shock spring, engine case, and side panel. Common mistake: ignoring a close contact point that only touches when the suspension compresses. Cycle the rear suspension by hand to confirm no contact.
6. Torque the header flange nuts evenly: Tighten the flange nuts in a cross pattern to the torque figure in your Honda service manual. Common mistake: over-tightening one nut, which warps the flange and causes a leak. Use a calibrated torque wrench, not a guess.
7. Torque the muffler mounts and header joint: With the header secure, tighten the muffler-to-header joint and frame mounts to the supplied or manual specification. Common mistake: leaving the muffler mount loose, which allows vibration and cracking. Grab the muffler and check for movement before starting.

Product facts

• CRF450R/RX 2021-2024 / CRF450R-S 2023-2024 RS-12 Stainless Full Exhaust, w/ Stainless Muffler: The RS-12 stainless full exhaust is the #1 exhaust in Supercross and Motocross and powered Chase Sexton to the 2023 450 Supercross title and Jett Lawrence to the 2023 450 Motocross SMX title and a perfect season. That race pedigree means the system is designed for competition use, so install it with the same attention to clearance and torque that a race team would.