3/4 System Exhaust Instructions

Removal

1. Remove the seat, plastic panel under the headlight, left side storage container, and left side main plastic body panel.

2. Unplug the oxygen sensor from the vehicle’s electrical harness and route the wiring so it is free from the vehicle.  The connector is located under the seat. Remove the sheet metal heat shield near the oxygen sensor.

3. Remove the hardware connecting the front cylinder head pipe to the factory silencer inlet.

4. Remove the nuts holding the rear cylinder head pipe to the rear cylinder. (Save these nuts)

5. Remove the factory silencer/rear head pipe by removing the hardware holding the silencer to the vehicle. Discard the round gasket between the front cylinder’s head pipe and factory silencer inlet pipe as well, as the one between the rear head pipe and cylinder head.  These gaskets will likely have stayed with the factory silencer.

Installation

1. Loosely install the HMF rear head pipe (the longer pipe provided in the kit) using (1) of the provided 1.25” Flange Gaskets between the head pipe and cylinder head.  Loosely install the original nuts to keep the head pipe in place, do not tighten.(See Figure #1)

2. Loosely install the HMF mid-pipe (the shorter pipe provided in the kit) to the factory front head pipe using the provided (1) 1.25” Flange Gasket, (2) M8x25 Hex Bolts, (2) M8 Nylock Nuts, and (4) ¼” Washers.  Do not tighten.(See Figure #2)

If installed correctly the two head pipes will be slightly offset as shown below:(See Figure #3)

3. Slide the provided (2) #56 T-Bolt Clamps over the ends of the head pipes then install the HMF silencer.  Mount the silencer using the provided (2) M8x25 Hex Bolts, (4) ¼” Washers, and (2) M8 Nylock Nuts. Do not tighten the silencer mounting hardware at this point.  (See Figure #4)

4. Tighten hardware in the following order:

• Rear head pipe to cylinder nuts
• Front head pipe to HMF mid-pipe bolts
• (2) T-Bolt clamps at the silencer inlet pipes
• Silencer mounting hardware

5. Transfer the oxygen sensor from the factory exhaust and install it into the bung welded into the HMF exhaust.  It is recommended to apply a small amount of anti-seize to the threads of the sensor before installing. Snug down the sensor. Re-install the heat shield and route the wiring for the oxygen sensor through the shield in the same way it was installed from the factory.  

NOTE: Due to variances in the machine from the factory you may need to slightly bend the large washer on the oxygen sensor or modify the opening on the heat shield.  Do not run the HMF exhaust without this heatshield or damage to the body panels may occur.(See Figure #5)

6. Inspect the entire exhaust system for proper clearance and fitment, adjust as necessary.

7. Reinstall all previously removed parts and body panels.

NOTE: All HMF exhaust for the Brute Force 750 requires fuel tuning.  Visit https://www.hmfracing.com/tuning to see options for your machine.  

Updated: 1/7/19