How to Install a Pro Moto Billet Spark Arrestor on Honda CRF250R (2004-2005)

The Pro Moto Billet PMB-01-1100 Spark Arrestor is designed to convert the stock muffler on the 2004-2005 Honda CRF250R into a U.S.F.S. approved spark arrested muffler. This guide follows the manufacturer installation process and reformats it for easier use on CRFsOnly.com.

⚠️ Before You Start

• Read the instructions completely before starting.
• You will not be able to reuse the stock end cap after installation.
• If you are not comfortable drilling, cutting, or modifying exhaust components, have the installation performed by a qualified technician.

🧰 Parts Included

• 1 Spark Arrestor Base
• 1 Nozzle
• 1 Screen
• 3 M6 Bolts
• 8 Self-Tapping Screws

🛠️ Tools Required

• Drill
• 13/64" drill bit
• Flat screwdriver
• Hammer
• Hacksaw
• Center punch
• High-temperature silicone sealant

🔧 Step-by-Step Installation

Step 1: Remove the Exhaust and Secure It

Remove the exhaust pipe from the bike and clamp the mounting tab securely in a vise. Place something between the vise jaws and the mount to prevent marring the aluminum mount.

Step 2: Break the Epoxy Seal

Use a flat screwdriver and hammer to break the epoxy seal around the aluminum end cap and the steel inner core of the exhaust pipe.

Step 3: Drill Out the Rivets

Using a 13/64" drill bit, drill out the rivets holding the stock end cap in place. Make sure to remove the rivet heads completely.

Step 4: Punch the Remaining Rivet Material Through

Use a center punch and hammer to push the remaining rivet material through the holes and out of the stock end cap.

Step 5: Remove the Stock End Cap and Inner Core

Using a flat screwdriver and hammer, push the end cap out of the exhaust canister. Move around the end cap evenly so it comes out straight. The perforated inner core is welded to the stock end cap, so they will come out together. If needed, a heat gun on the canister sleeve can help loosen things up.

Step 6: Remove the Core from the Packing

Carefully remove the end cap and perforated inner core from the packing material.

Step 7: Save and Protect the Packing Material

Remove all old rivet pieces from the packing material inside the muffler canister, then carefully remove the packing. You will reuse it, so keep it in its bag. If the bag tears, tape it back together before reinstalling.

Step 8: Separate the End Cap Components

Separate the aluminum portion of the stock end cap from the steel inner core.

Step 9: Cut the Perforated Inner Core

Using a hacksaw, cut the perforated inner core from the steel portion of the end cap. Make the cut directly in front of the steel portion of the end cap.

Step 10: Test Fit the Spark Arrestor Base

Test fit the spark arrestor base to make sure the inner baffle is cut to the correct length.

Step 11: Deburr the Cut Edge

Use a file to remove any sharp edges from the cut-off portion of the perforated inner core.

Step 12: Rewrap the Packing

Smooth out the fiberglass packing material and wrap it tightly around the perforated inner core.

Step 13: Reinstall the Core and Packing

Install the perforated core and fiberglass packing into the muffler canister. Make sure the end of the perforated core with the L-shaped stopper goes in first so the core stays retained after installation.

Step 14: Apply High-Temp Silicone

Apply high-temperature silicone sealant to the outer stepped portion of the spark arrestor base and generously to the surface where the perforated inner core will be retained. High-temperature silicone is required to prevent vibration.

Step 15: Install the New Spark Arrestor Base

Install the new spark arrestor base and make sure it is pushed up tight against the muffler.

Step 16: Install the Self-Tapping Screws

Install one self-tapping screw at a time by drilling a 13/64" hole at each original rivet location. Each time you drill and install a screw, make sure the base stays pushed tightly against the muffler. Lubricant such as WD-40 can help when installing the self-tapping screws.

Step 17: Clean Excess Sealant

Clean up any excess silicone sealant.

Step 18: Install the Screen and Nozzle

Insert the spark arrestor screen and install the turndown nozzle using the supplied M6 bolts

🛠️ Maintenance & Inspection

• Inspect the spark arrestor screen regularly.
• Check during routine maintenance like air filter service or oil changes.
• Clean the screen to maintain airflow and performance.

⚠️ Important Safety Notice

A damaged or clogged spark arrestor will not function properly. If the screen develops holes or excessive buildup, it must be replaced immediately.

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