How To Make Sr 400 Slip On Exhaust: A Diy Guide

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So, you’re looking to spice up your Yamaha SR400 with a new slip-on exhaust? Excellent choice! It’s a fantastic way to enhance the bike’s aesthetics, and often, improve its sound and performance. This guide is designed to walk you through the process of crafting your own slip-on exhaust, step by step.

Building your own exhaust can be a rewarding experience, giving you a sense of accomplishment and allowing for customization that you might not find with off-the-shelf options. We’ll cover everything from choosing the right materials to the final installation. This project requires some basic mechanical skills and tools, but don’t worry, we’ll break it down into manageable chunks.

Whether you’re aiming for a classic look, a louder growl, or a slight performance boost, this guide will provide the knowledge you need to succeed. Let’s get started and transform your SR400 into an even more head-turning machine!

Table of Contents show

Understanding the Sr400 Exhaust System

Before we dive into the build, let’s get familiar with the SR400’s exhaust system. The stock exhaust typically consists of a header pipe (that connects to the engine), a catalytic converter (often integrated into the stock muffler), and the muffler itself. A slip-on exhaust replaces the muffler, connecting to the existing header pipe.

Understanding this structure is key. We’re essentially swapping out the rearmost component. The header pipe’s dimensions and the connection points are crucial for a proper fit. Also, consider the catalytic converter’s role, as removing it might affect emissions and potentially performance, depending on your local regulations.

Components of the Stock Exhaust

Header Pipe: Connects to the engine’s exhaust port.
Catalytic Converter (Integrated): Reduces emissions.
Muffler: Silences exhaust sounds.
Clamps/Fasteners: Secure the exhaust components.

Planning Your Sr400 Slip-on Exhaust

Careful planning is essential. This includes deciding on the type of exhaust, the materials you’ll use, and the tools you’ll need. This stage will determine the success of your project.

Choosing Your Exhaust Style

There are several styles to consider. Each offers a different look and sound. Consider these options:

Shorty Exhaust: A shorter, often stubbier design. Favored for its aggressive look and increased sound.
Megaphone Exhaust: Tapers outward, creating a distinctive aesthetic and often a louder tone.
Cone Exhaust: A conical shape, offering a classic cafe racer look.
Reverse Cone Exhaust: A cone that tapers inward, giving a unique visual appeal.
Straight-Through Muffler: A simple cylinder design, often with internal baffling.

Consider the aesthetic you’re aiming for. Do you want a vintage, modern, or custom look? Also, think about the sound. Do you want a louder exhaust? Research the different styles online by watching videos or listening to audio clips to help you decide.

Material Selection

The choice of materials affects the exhaust’s durability, sound, and appearance. Here are the most common options:

Stainless Steel: Corrosion-resistant, durable, and has a sleek appearance. It’s a popular choice for its longevity.
Mild Steel: More affordable, but susceptible to rust. It’s a good option if you’re on a budget but will require more maintenance or coating.
Aluminum: Lightweight, but less durable than steel.
Titanium: Very lightweight and strong, but also expensive.

Stainless steel is generally the best balance of cost, durability, and aesthetics for this project.

Required Tools and Materials

Here’s a comprehensive list of what you’ll need: (See Also: Won Hundred Willow Slip On Sneakers )

Stainless Steel Tubing: Appropriate diameter for your desired exhaust style. (e.g., 1.5″ to 2″ depending on the design and whether you’re building a full system or just the slip-on section).
Muffler Packing: High-temperature packing material to absorb sound.
End Caps: For the muffler.
Welding Equipment: TIG welder is preferred for stainless steel, but MIG can work with proper setup.
Welding Helmet and Gloves: Safety first!
Angle Grinder: For cutting and shaping metal.
Cutting Discs: For the angle grinder.
Grinding Discs: For smoothing welds.
Measuring Tools: Tape measure, ruler, calipers.
Clamps: To hold pieces together during welding.
Safety Glasses: Crucial for eye protection.
Respirator: To protect against welding fumes.
Gloves: Protect your hands.
Drill and Drill Bits: For mounting holes.
Metal File: For deburring edges.
Spray Paint (High-Temperature): Optional, for coating the exhaust.
Clamps: For securing the slip-on to the header pipe.

This list is a starting point, and you may need other tools or materials depending on your chosen design and specific needs.

Step-by-Step Guide to Making the Slip-on Exhaust

This section provides a detailed guide for constructing your slip-on exhaust. Remember to prioritize safety throughout the process.

1. Preparation and Design

Before you start cutting and welding, create a design. Measure the existing header pipe’s diameter and the length you want your new exhaust to be. Sketch the design, including the desired muffler shape, length, and any bends or transitions. This will serve as your blueprint.

Consider where you want to mount the exhaust. You might need to fabricate a bracket or utilize the existing mounting points on your SR400. Accurately measure and plan for these mounting points.

2. Cutting and Shaping the Tubing

Use the angle grinder with a cutting disc to cut the stainless steel tubing to the required lengths based on your design. Make clean, straight cuts. Use a metal file to deburr the edges after cutting to remove sharp edges.

If your design includes bends, you’ll need to either use pre-bent tubing or bend the tubing yourself using a pipe bender. Be careful when bending the tubing, as kinking can affect exhaust flow. For slip-on exhaust, bends are less common, but they may be required for optimal aesthetics.

3. Welding the Components

This is where the welding equipment comes into play. If using a TIG welder, ensure you have the correct settings for stainless steel. If using a MIG welder, use the correct wire and gas (usually a mix of argon and CO2).

Tack weld the pieces together first to hold them in place. Then, carefully weld the seams, ensuring full penetration and a clean weld bead. For the muffler, weld the end caps to the tubing. Practice your welds on scrap metal before working on the final pieces.

If you’re not experienced with welding, consider practicing before starting or seeking help from someone with welding experience. Poor welds can lead to exhaust leaks and structural failure.

4. Preparing the Muffler

If you’re building a muffler, you’ll need to pack it with muffler packing material. Wrap the packing around a perforated core (if your design includes one) or directly inside the muffler body. (See Also: Will Two Brothers Slip On Exhaust Work For Rebel 300 )

Ensure the packing is tightly packed to effectively absorb sound. Over-packing can restrict exhaust flow, but under-packing will result in a louder exhaust.

5. Finishing and Finishing Touches

Once the welding is complete, grind down any rough welds to create a smooth finish. This improves appearance and can help with exhaust flow.

Consider polishing the stainless steel for a shiny finish or applying high-temperature spray paint for a more subdued look or to match your bike’s aesthetic. Allow the paint to dry completely before installation.

6. Installation on the Sr400

Carefully slide the slip-on exhaust onto the existing header pipe. Use the appropriate clamps to secure it firmly. Ensure the exhaust is aligned correctly and doesn’t interfere with any other components on the bike.

Double-check all connections and mounting points to ensure the exhaust is secure. Start the engine and listen for any exhaust leaks. If you hear leaks, tighten the clamps or re-weld any faulty welds.

Tips for Success

Here are some helpful tips to ensure a successful outcome:

Take Your Time: Don’t rush the process. Rushing can lead to mistakes.
Practice Welding: Practice your welding skills on scrap metal before working on the final exhaust.
Safety First: Always wear appropriate safety gear, including a welding helmet, gloves, and a respirator.
Measure Twice, Cut Once: Accurate measurements are crucial.
Test Fit: Regularly test-fit the exhaust on your SR400 during the build process to ensure everything aligns correctly.
Seek Advice: Don’t hesitate to ask for help from experienced welders or mechanics.
Research: Watch videos and read other guides to gain more insights.

Troubleshooting Common Issues

Here are some common problems and how to solve them:

Exhaust Leaks: Check the clamps and welds. Tighten the clamps or re-weld any leaks.
Poor Sound Quality: Ensure the muffler packing is correctly installed. Adjust the packing if necessary.
Poor Performance: Check for any restrictions in the exhaust flow. Ensure the exhaust is not too restrictive.
Difficulty Welding: Adjust your welding settings or seek help from an experienced welder.
Exhaust Doesn’t Fit: Double-check your measurements and design. You may need to modify the design or header pipe.

Modifying the Sr400’s Carburetor

When you change the exhaust, the engine’s air-fuel mixture might be affected. This is because the exhaust system influences the engine’s backpressure, which affects how the engine breathes. If you significantly increase exhaust flow (e.g., from a stock exhaust to a free-flowing slip-on), the engine might run lean, meaning there’s too much air and not enough fuel. This can lead to poor performance, overheating, and even engine damage.

To address this, you might need to adjust the carburetor. This typically involves changing the main jet, pilot jet, and/or adjusting the needle position. The specific adjustments depend on your exhaust setup and the bike’s overall performance. It’s often best to consult a mechanic or experienced SR400 owner for guidance on carburetor tuning.

You can also consider installing a performance air filter, which allows more air into the engine, and then tuning the carburetor to match. This can further improve performance. (See Also: Will You Lose Low End With M4 Slip On Fz07 )

Carburetor Adjustment Steps (general)

Identify the Carburetor: Locate your SR400’s carburetor (usually a Mikuni BS34).
Access the Jets: You’ll typically need to remove the float bowl to access the main jet and pilot jet.
Determine the Jet Sizes: Research the recommended jet sizes for your exhaust and any other modifications.
Replace the Jets: Carefully remove the existing jets and install the new ones.
Adjust the Needle: The needle controls the fuel flow in the mid-range. Adjust the needle clip position if needed.
Fine-Tune: Start the engine and fine-tune the carburetor based on the engine’s performance. You might need to adjust the idle mixture screw.

Disclaimer: Carburetor tuning can be complex and requires some mechanical knowledge. If you’re not comfortable, seek professional help.

Legal Considerations

Before you begin, consider the legal implications of modifying your exhaust. Regulations regarding exhaust noise and emissions vary depending on your location. Some areas have strict noise limits, while others may require catalytic converters to meet emissions standards. Ensure your modified exhaust complies with local laws.

Removing the catalytic converter might be illegal in some regions. Check the regulations in your area to avoid fines or other penalties.

Maintaining Your Custom Exhaust

Proper maintenance will extend the life of your custom exhaust. Here are some maintenance tips:

Regular Inspection: Inspect the exhaust for any signs of damage, such as cracks, dents, or rust.
Cleaning: Clean the exhaust regularly to remove dirt and grime.
Rust Prevention: If your exhaust is made of mild steel, apply a rust preventative coating.
Welds: Check the welds for any signs of cracking or deterioration.
Muffler Packing: Replace the muffler packing periodically, as it degrades over time.

Further Customization Possibilities

Once you’ve built your slip-on exhaust, there are many ways to further customize your SR400:

Header Pipe Modifications: You can also replace the header pipe for improved performance and aesthetics.
Powder Coating: Consider powder coating your exhaust for a durable and visually appealing finish.
Heat Shields: Add heat shields to protect yourself and the bike from exhaust heat.
Custom Brackets: Fabricate custom brackets for a unique look.

The possibilities are virtually endless. Let your creativity run wild!

Verdict

Building a slip-on exhaust for your Yamaha SR400 is a rewarding project that can significantly enhance your bike’s appearance and sound. By carefully planning, selecting the right materials, and following the steps outlined in this guide, you can create a custom exhaust that perfectly suits your style and preferences.

Remember to prioritize safety, take your time, and don’t be afraid to seek help if needed. With a little effort and attention to detail, you’ll be cruising down the road with a unique and personalized SR400 that turns heads wherever you go. Enjoy the process, and the satisfaction of building something with your own hands!

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Finally, remember to consider the legal aspects of exhaust modifications and adhere to local regulations. Enjoy your ride and the distinctive sound of your custom-built exhaust!