How to Properly Install the RMH Performance Copperhead XL

by Reginald M Higgs, Jr.

Installing the RMH Performance Copperhead XL Pipe on a Felt Faker Frame

The RMH Performance Copperhead XL is a massive, high-performance stainless steel expansion chamber designed for large-bore engines (80cc–125cc). Mounting this oversized pipe onto a Felt Faker gas-tank frame requires precise alignment to ensure the header clears the downtube and the wide belly is in the optimal position for riding.

 

🛠️ Required Tools & Components

  • RMH Expansion Chamber Kit (Includes slip-fit header, expansion belly, springs, silencer, silencer mount and side mount)

  • CNC Front Engine Mount (Essential for setting correct engine height and angle on Felt Faker frames)

  • Rubber Isolation Bushing (To place between the frame/clutch bracket and the pipe tab)

  • High-temp copper exhaust gasket & RTV silicone 

 

 

📐 Step 1: Optimize Engine Positioning

Felt Faker frames offer a tight squeeze for oversized pipes. Before touching the exhaust, check your engine placement:

  1. Use an adjustable CNC front engine mount.

  2. Adjust the engine angle so that it sits as neutral or slightly nose-down as your rear mounts allow. This precise angling is critical to keep the thick header pipe from resting directly against the frame's fat down-tube. 

  3. Leave all engine mounting bolts loose until proper pipe position is established.

⚙️ Step 2: Fit the Slip-Fit Header

  1. Mount the exhaust flange to your cylinder exhaust port using a fresh copper gasket and a skim of high-temp RTV silicone. Tighten the port studs evenly.

  2. Insert the slip-fit header into the main expansion chamber pipe body.

  3. Coat the slip joint lightly with high-temp sealant to block oil leaks before securing it with the provided retention tension springs. 

🔧 Step 4: Secure the Side Mount (Anti-Vibration)

Never rigid-mount a stainless steel expansion chamber directly to an aluminum frame, or the weld points will fracture. 

Bolt the RMH chrome side-mount bracket to your engine’s clutch cover. Note: Depending on the specific variant of your Faker frame, you may need to add metal spacers behind the engine cover plate to perfectly square up the mount. 

Place a rubber isolation bushing sandwich style between the pipe’s mounting tab and the bracket. 

Tighten the bolts securely. The rubber spacer handles lateral frame flex and isolates the stainless steel from destructive engine harmonics.

 

⚠️ Post-Installation Check

Double-check that the exhaust components do not make contact with any raw painted surfaces on your Faker frame. Start the bike and inspect the slip-fit joints for escaping smoke. Retighten the cylinder header nuts after your first 30-minute heat cycle. 

 

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