Spark Exhaust Bent Tube 90° Ø 40 × 1.0 mm Stainless Steel Universal G9103

Forty millimetres through ninety degrees. Together with the 45 at the same diameter, this is most of what a custom system is built from.

Key Features

• Mandrel-formed 90° bend, AISI 304 stainless steel.
• Ø 40 mm outside, 1.0 mm wall thickness.
• Straight tangents at both ends.
• Matches Spark's 40 mm straight tube, article G9001.
• Spark part number G9103, made in Mantova, Italy.

The Two-Bend System

A right angle off the collector and a forty-five into the silencer position covers a large proportion of one-off builds. The ninety does the turn where space is tightest and the geometry is least negotiable; everything after it is aiming.

A straight between the two turns a pair of fixed angles into an adjustable layout, and the length of that straight is usually the last thing decided.

Where the Loss Actually Is

Not in the corner itself but just after it. Gas leaving a sharp bend is separated from the inside wall and takes several tube diameters to reattach. Anything placed in that region — a second bend, a sensor boss, a joint — sees disturbed flow.

Leaving a short straight after a ninety costs nothing and recovers most of it.

Sweep and Clearance

A production ninety at this diameter occupies a square roughly a hundred millimetres on a side once the tangents are counted. That is the space it needs, and it is worth drawing before ordering: the most common surprise on a first build is a bend that fits the pipe run and not the motorcycle.

Half a Ninety

Cut at the apex, this bend gives two forty-fives — each with a straight tangent on one end and a cut on the other. Useful to know when a job needs one right angle and one shallow corner and only one article is on the shelf.

Distortion as It Cools

A weld pulls as it solidifies, and on a right angle that pull acts across the corner rather than along a line. Tack at four points, check with a square, and run the bead in opposing quarters — a ninety welded continuously round from one side is not a ninety afterwards.

Buy the Angle You Can Reduce

A right angle can become anything shallower with a saw. A thirty cannot become anything larger. Where the geometry is not yet settled, the sharper article is the safer one on the bench.

Ordering

One bend per article. Spark builds 30°, 45° and 90° at this diameter.