90 Degree Bend Piping: Planning a Custom Exhaust Route
By Yoshimura R&D of America, Inc. | Published: 2026-10-16
Category: How-to Guides
Plan a custom exhaust route that flows, fits, and lasts. Learn how to choose 90 degree exhaust bends, avoid routing mistakes, and weld stainless tubing cleanly.
Quick answer
Plan the full exhaust route on the bike before cutting anything. Use 90 degree exhaust bends only where the path truly turns, keep the tubing as straight as possible between bends, and leave enough straight sections for clamps and welds. A mandrel-bent 304L stainless bend like Builder Series 90 Degree Bends gives you a clean, consistent starting point for custom exhaust piping.
Map the route before you buy bends
Start at the cylinder head flange and work back to the muffler. Use a length of stiff wire or thin PVC to mock the centerline, then measure each straight run and each turn. Mark where the pipe must clear the swingarm, shock, footpeg, and bodywork at full suspension travel. Measure the outside diameter of your header outlet and muffler inlet so you order bends that match. If you are unsure of a size, check the product page or call Yoshimura at 800-634-9166 before ordering.
Choose bend radius, wall thickness, and material
A tight radius saves space but disturbs flow more than a wide radius. For most street and dual-sport builds, a centerline radius around 2.5 to 3 times the tube diameter is a practical compromise. Wall thickness matters for welding: 1mm is common in aftermarket stainless and welds well with TIG. Builder Series 90 Degree Bends are 304L stainless with a 1mm wall, full mandrel bent on an all-electric CNC bender to minimize clamping or forming marks. Each bend is inspected against CAD and the ends are cut to length and deburred, so you get a perpendicular end condition for welding. The mill finish is ready for welding and any post-weld finish you choose, such as polish, sandblast, or ceramic coating.
Lay out cuts and tack welds in order
Cut one piece at a time and tack it in place on the bike. Work from the flange backward so the header stays aligned. Use a spacer or a small block to hold the gap between the pipe and the frame, and check clearance with the suspension fully compressed and fully extended. Keep straight sections at least two tube diameters long between bends; this reduces stress and gives you room to clamp or weld. Do not fully weld until the entire route is tacked and the muffler sits where you want it.
Secure the system and check for leaks
After final welding, let the pipe cool, then install it with fresh gaskets and proper clamps. A clamp like the TRS Muffler Clamp Carbon Fiber W/Heatshield is designed to tighten connecting points on your Yoshimura system; if you cannot find the right clamp for your setup, contact Yoshimura directly. Start the bike and listen for ticking or hissing at each joint. Recheck clamp torque after the first heat cycle, because stainless expands and contracts as it warms and cools.
Step-by-step exhaust routing plan
- Mock the route with wire or PVC: Run a mock centerline from the head flange to the muffler. Mark every point where the pipe must clear the swingarm, shock, footpeg, and bodywork at full suspension travel. Checkpoint: if the mock pipe touches anything at full compression, adjust the route before buying bends.
- Measure and order bends and straight tubing: Match the outside diameter of your header outlet and muffler inlet. Choose a bend radius that fits your space and a wall thickness that suits your welding process. Order 90 degree bends and straight sections to cover the measured runs. Checkpoint: confirm sizes against the product page or call Yoshimura at 800-634-9166 if you are unsure.
- Cut and tack one piece at a time: Work from the flange backward. Cut each piece slightly long, trim to fit, and tack it in place on the bike. Keep straight sections at least two tube diameters long between bends. Checkpoint: do not fully weld until the whole route is tacked and the muffler sits in its final position.
- Final weld, install, and heat cycle: Complete the welds, let the pipe cool, then install with fresh gaskets and the correct clamps. Start the bike and listen for leaks at each joint. Checkpoint: recheck clamp torque after the first heat cycle, because stainless expands and contracts as it warms and cools.
Parts that help with custom routing
- Builder Series 90 Degree Bends: Builder Series 90 Degree Bends are 304L stainless steel with a 1mm wall thickness, full mandrel bent on an all-electric CNC tube bender to minimize clamping or forming marks. Mandrel bending keeps the inside of the bend smooth, which supports better flow than a crush-bent pipe and gives you a consistent starting point for welding.
- Builder Series 90 Degree Bends: Tube ends are cut to length and deburred for a clean, perpendicular end condition, and the mill finish is ready for welding and any desired post-weld finishing. You spend less time grinding and squaring ends, and you can choose your final finish after the welds cool.
- TRS Muffler Clamp Carbon Fiber W/Heatshield: The TRS Muffler Clamp Carbon Fiber W/Heatshield is a replacement service part for tightening connecting points on your Yoshimura exhaust system. Using the correct clamp helps keep joints tight and reduces the chance of leaks or movement after heat cycles.
